Zeitschriften und Ausgaben

Volumen 26 (2019): Heft 4 (December 2019)

Volumen 26 (2019): Heft 3 (September 2019)

Volumen 26 (2019): Heft 2 (June 2019)

Volumen 26 (2019): Heft 1 (March 2019)

Volumen 25 (2018): Heft 4 (December 2018)

Volumen 25 (2018): Heft 3 (September 2018)

Volumen 25 (2018): Heft 2 (June 2018)

Volumen 25 (2018): Heft 1 (March 2018)

Volumen 24 (2017): Heft 4 (December 2017)

Volumen 24 (2017): Heft 3 (September 2017)

Volumen 24 (2017): Heft 2 (June 2017)

Volumen 24 (2017): Heft 1 (March 2017)

Zeitschriftendaten
Format
Zeitschrift
eISSN
2354-0133
Erstveröffentlichung
20 Dec 2019
Erscheinungsweise
4 Hefte pro Jahr
Sprachen
Englisch

Suche

Volumen 25 (2018): Heft 2 (June 2018)

Zeitschriftendaten
Format
Zeitschrift
eISSN
2354-0133
Erstveröffentlichung
20 Dec 2019
Erscheinungsweise
4 Hefte pro Jahr
Sprachen
Englisch

Suche

53 Artikel
Uneingeschränkter Zugang

Manoeuvring Characteristics of the Push Train with an Auxiliary Steering Device

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 7 - 13

Zusammenfassung

Abstract

The carried out and planned studies on the revitalisation of Odra and Vistula rivers in Poland and restoration of regular inland navigation put a great attention into environmental issues related to the operation of inland waterborne transport means. The design and operational parameters of inland ships and convoys are dependent on waterways dimensions and their influence on the environment. The article presents problems related to manoeuvring performance of the push train, which is the most popular inland waterborne means of freight transport in Poland and in Europe. The alternative auxiliary steering device improving push train manoeuvrability has been tested on the physical model of a push barge. The active bow steering device consisted two bow rotors has the influence on the operational safety of the push train with respect to improved manoeuvring characteristics and decreased impact on the environment, port and lock facilities, ships and boats in narrow passages. The results of model tests presented in the article allowed for estimation of turning ability of the push train with and without bow rotors. A significant difference was observed with respect to the manoeuvring area, distances of advance, tactical diameter, and time of the manoeuvre.

Schlüsselwörter

  • inland push train manoeuvrability
  • manoeuvrability criteria
  • bow rotor
Uneingeschränkter Zugang

The Magnetic Field Curvature Correction Algorithm Dedicated for Helmet Mounted Cueing Systems

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 15 - 30

Zusammenfassung

Abstract

The article presents the new built in Poland helmet mounted cueing system NSC-1 Orion with a magnetic method, dedicated to the multi-purpose helicopters W-3PL Gluszec. This system uses the magnetic field generated by the system of three mutually orthogonal electric coils. The principle of operation of this system is described and the method of determining the angular position of the pilot’s helmet relative to the helicopter’s cabin using the reference magnetic field and the directional cosines matrix are discussed. Electrical flat coils, constructed in the Polish Air Force Institute of Technology (AFIT), generating a magnetic field with curved symmetry axis characteristics, causing errors in determining the angular position of the pilot’s helmet are shown. As a way to minimize these errors, an original proprietary algorithm for correcting the negative impact of the magnetic field curvature generated by the on-board system has been presented. Mathematical relations describing the presented correction process as well as selected results of simulation and experimental investigations in the area of inaccuracy of the “before” and “after” systems of applying the developed algorithm were given. Inaccuracies determined from computer simulations of the developed mathematical relations were compared with experimental data from magnetic field measurements using the integrated three-axis sensor ADIS-16405, used in the laboratory of the AFIT Avionics Division for helmet control of the angular position of the moving observation and sighting head and reflector-search light.

Schlüsselwörter

  • transport
  • avionics
  • helmet-mounted cueing systems
  • errors of the angular positioning
  • magnetic field measurement
  • flat coil profile modelling
Uneingeschränkter Zugang

Vegetable Oils as Additives to Improve the Lubricity of Low-Sulphur Fuels

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 31 - 36

Zusammenfassung

Abstract

The aim of the study was to determine the sulphur content in 33 samples of oils pressed from different species of vegetable. The unconventional oil samples were purchased from commercial store. Oils was analysed in terms of sulphur content according to the method using X-ray fluorescence spectrometry with wave dispersion, that is described in the PN-EN ISO 20884, 2012 standard. Obtained results of sulphur analysis were presented as the arithmetic mean ± standard deviation (from three replicates) and statistically analysed using the Statistica 13.0 PL program. In order to indicate significance of differences between oils analysis of variance (ANOVA) with Tukey’s test of p ≤ 0.05 significance level was used. The statistical analysis indicated significant differences in the content of sulphur content in the analysed vegetable oils, which could affect the lubricity of prepared fuel blends and in some cases significantly, increase the sulphur content above acceptable value 10 ppm. It was concluded that vegetable oils could be a suitable raw material improving the lubricating properties of low-sulphur diesel oils. However, due to significant differences in the sulphur content in the analysed samples, the content of this element should be analysed beforehand in order to eliminate the possibility of exceeding the permissible level of sulphur in transport fuels.

Schlüsselwörter

  • sulphur content
  • different species
  • vegetable oils
  • biofuel production
  • lubricity
Uneingeschränkter Zugang

Review of Loss Models for High Pressure Turbines

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 37 - 44

Zusammenfassung

Abstract

This article presents a literature review about the physical analysis of the loss models, which are used in off-design procedure for high-pressure turbines.

A high-pressure turbine is designed to have maximum performance at design point. However, engines are operating in different conditions, and the comprehension of off-design conditions is very important. The loss mechanisms are very complex and predictions considering empirical methods are a good approach to have preliminary results. Based on these results, different researches have proposed theories about the loss mechanisms, and over the time, these models have been modified to describe better the phenomena involved between blades and flow. Once the physical mechanisms behind the loss models are known, it is possible to compare them and understand the reason why the results given for some methods present a higher agreement to experimental or numerical data.

In this framework, 2D numerical simulations of the flow around the blades of an axial high pressure turbine with different off design conditions have been realized, by using ANSYS FLUENT® code, to show the losses described by some of these models. Using these simulations a loss model has been selected and implemented in Matlab® to compare its results with the experimental data found in literature.

Schlüsselwörter

  • turbomachinery
  • gas turbines
  • high-pressure turbine
  • HPT
  • loss models
Uneingeschränkter Zugang

The Impact of Unevenness and Instability of Flue Gas Temperature on the Technical Condition of Gas Turbine Blades

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 45 - 51

Zusammenfassung

Abstract

Gas turbines are used in the power sector, aviation, pump houses, and other technical systems. Such a broad range of application is associated with favourable indicators: high power, rather low weight per unit of power, significant efficiency, as well as high durability. All of these indicators greatly depend on the combustion chamber flue gas temperature. It is important for the flue gas temperature to be uniform around the turbine perimeter and stable over time. This condition is extremely important also in the case of frequent temperature variations associated, e.g. with a variable operating range of a manoeuvre aircraft turbojet engine. The paper analyses the causes for the unevenness and instability of combustion chamber flue gas temperature. The impact of the fuel quality, the technical condition of the fuel supply system, as well as the operating conditions of the combustion chamber-turbine assembly was shown. The issues regarding the presence of various types of damage to turbine elements, their blades in particular, were defined. The main cause behind the damage is the unevenness and instability of flue gas temperature, resulting in the presence of overheating, creeping, thermal fatigue, high-temperature corrosion of blade material. The forms of that damage, especially the first turbine stages, were presented. Blade material microstructure test results showed increased layer thickness, grain-size, and especially, adverse modification of the strengthening γ’ phase in the temperature function. It was concluded periodic diagnostics of turbine blades with the optical method enables the non-invasive evaluation of their technical condition and drawing conclusions in terms of their durability.

Schlüsselwörter

  • flue gas temperature
  • gas turbine
  • blade
  • diagnostics
  • technical condition
Uneingeschränkter Zugang

Analysis of Operating States of Haul Trucks Used in Surface Mining

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 53 - 58

Zusammenfassung

Abstract

Mining transport system based on the use of haul trucks should result from thorough analysis of technical and operating issues – which can have a crucial impact on the cost of minerals extraction. This selection should consider hitherto disregarded criteria, such as technical infallibility, operating parameters like mean operating time between failures (MTBF), mean failure intensity and fault modes and effect analysis etc. Considering the above issues, the following article is an attempt to analyse operating parameters of transport fleet of haul trucks for mineral resource in surface mining. Diagram of the typology of technical and operational haul truck states; source: own study; mean failure intensity graph and mean failure intensity graph for the total observation time; relationships between mean expected time between consecutive failures of specific object and (MTBF) mean value of the time, in which specific equipment is in the down time due to a failure are presented in the article. The MTBF index is a basic parameter helpful to determine dependability and can be used for logistic planning, in particular in the field of spare parts. This index allows determining the cost of object use throughout its entire life cycle.

Schlüsselwörter

  • surface mining
  • haul truck
  • fault modes and effect analysis
  • operating states
Uneingeschränkter Zugang

The Preliminary Research of the Influence of Grease Microcontainers Made on the Surface of the Slide Association on the Vibration Signal Recorded for this Association

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 59 - 67

Zusammenfassung

Abstract

There is shown the construction of an elaborated test stand for the test research of sliding friction associations. The following properties of tested friction associations are described: type (chemical composition) and hardening of applied materials, as well as the results of the analysis of topography of their collaborating surfaces (base material and then after creating grease microcontainers in it). The methodology and the range of performed researches are described. The researches were conducted using the accelerometer A0760GP and the industrial measurement device Emerson CSI 2130. On the basis of recorded vibration signals, their amplitude spectra were determined. These spectra were being compared and analysed in reference to the possibilities of application of measurements of vibration signals to indication of the process of association wear. It was found that the process of wear of the tested sliding association without lubrication from grease microcontainers is visible as the change of form of vibration signals recorded for this association as even over-a-dozen-fold changes in the value of amplitudes of some special harmonic components of those signals, especially high-frequency components within the analysed range of frequencies. It was also found that the application of the grease microcontainers on the surface on which rollers slide (not roll) allowed to acquire a significant reduction of the process of wear of the tested slide association, showed by the slower pace of growth of the value of all harmonic components, especially high-frequency components within the analysed range of frequencies. At the end there were provided directions of further researches.

Schlüsselwörter

  • vibration
  • slide association
  • friction
  • wear
  • grease microcontainers
Uneingeschränkter Zugang

Deviation Angle Models in off-Design High-Pressure Turbines

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 69 - 74

Zusammenfassung

Abstract

In the article, a set of deviation angle models, which are used to predict the off-design performance high-pressure turbines, has been presented, basing on a literature study. The deviation angle is a deviation between the actual flow angle and the blade inclination angle. It is an essential parameter in turbine performance evaluation. This angle shall be obtained accurately in 1-D design and evaluation, so as to ensure the validity of blade profiling and calculation results. If deviation angle is ignored, the turbine will produce a lower change of tangential velocity, and consequently a lower torque, output work and enthalpy drop than intended by the designer. For this reason, the deviation angle model needs to be established. There exist a number of different deviation models, resulting in varying degrees of flow deviation when applied. In the article, correlations for gas outlet angle, dependent on the Mach number at outlet and determined by the blade loading towards the trailing edge has been presented. The main difficulty in establishing the deviation model is a continuity in defining the angle for all speed ranges (both subcritical and supercritical). Each of the models presented in the article deals with this problem in a different way. A few deviation models, briefly discussed in the article, are based on experimental data and one is based on analytical approach.

Schlüsselwörter

  • turbomachinery
  • gas turbines
  • high-pressure turbine
  • HPT
  • deviation angle
Uneingeschränkter Zugang

Estimating the Main Dimensions of the Ship’s Hull

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 76 - 80

Zusammenfassung

Abstract

Preliminary ship owner’s assumptions for new ship consist of deadweight, speed-shipping line and others. Taking it as a base, in early stage of design one has to select propulsion type. This goal needs definition of principal dimensions of a vessel, which are the base for further calculations of hull’s resistance and evaluation of necessary power of main engine to fulfil shipping requirements. Selection of main dimensions of vessel is limited by rules regarding buoyancy, stability, hull strength, manoeuvring capability, and limitations related to seaways or harbours characteristic. In this article is presented the methodology of calculation of principal parameters of a vessel, necessary for calculation of displacement in relation to vessel’s type, volumetric coefficients, Froude number, and others values affecting ship’s dimensions. It is about midship section coefficient, waterline coefficient, prismatic coefficient. Those values are necessary for calculation of hull resistance. In the article, are presented major constraints for designing of new vessels coming from ship-owner assumptions such as seafaring limitations. In the table is presented comparison of results of calculations above-mentioned values of three type of vessels representing same displacement. There are also presented different calculation methods of transverse midship section coefficient and wet area coefficient, for 3 types of vessels (container vessel, bulk carrier and tanker with displacement of 120000 t.

Schlüsselwörter

  • seagoing ships
  • hull coefficient
  • hull dimensions parameters
Uneingeschränkter Zugang

Numerical Simulations of a Bird Strike Against a Helicopter Windshield

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 81 - 88

Zusammenfassung

Abstract

The article presents simulation results of a bird strike with a helicopter windshield of small helicopter category. It turns out that there are no certification requirements regarding windshield of this category. Therefore Agusta A109 helicopter as a representing this helicopter category has been chosen for researcher. The simulations were conducted on the basis of LS-DYNA software by means of the SPH method for bird model shape of cylinder with hemispherical endings for the speed of Vc = 285 km/h. The analyses regarded various angles of the bird model impact into windshield. As a result of the simulations, comparative analyses in the aspect of time curves of the kinetic energy, velocity, and windshield deformation were achieved. The analysis shows that at smaller angles of attack, the bird’s model has a higher speed at the moment of impact, and thus greater kinetic energy, because it did not lose speed as a result of the collision. In addition, the deflection of the windshield is smaller. In some cases, the deflection of the windshield may be observed, which indicates the elastic response of the system. In case of impact in the normal direction to the surface of the glass, the bird’s model practically pierces it. The use of a thicker pane translates into less deformation of the pane, but causes its destruction at the connection point with the helicopter carrier structure.

Schlüsselwörter

  • bird strikes
  • helicopter windshield
  • numerical analyses
  • LS-DYNA
Uneingeschränkter Zugang

Numerical Analysis of Influence of Bearing Material Thermal Conductivity Coefficient on Hydrodynamic Lubrication of a Conical Slide Bearing

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 89 - 96

Zusammenfassung

Abstract

One of the main parameters affecting the hydrodynamic lubrication of slide bearings is the viscosity of lubricating oil. Many studies show, that significant changes in the viscosity of oil occur along with changes in its temperature. The influence on the temperature distribution in the lubrication gap of the slide bearing have a variety of factors, and one of them is the amount of heat exchanged between the lubricant and the environment. The temperature of the lubricating oil of operating bearing is usually higher than the ambient temperature. In addition to the convection, which occurs during the flow (heat exchange related to the oil supply and discharge system) some amount of heat is transferred to the bearing sleeve material (and also to the bearing shaft), and then it is conducted to sleeve outer surface. The amount of heat transferred through the bearing sleeve is mainly dependent on the difference of temperatures between inner and outer sleeve surfaces and also depend on the heat conduction coefficient of sleeve material. This article presents the results of modelling of the influence of amount of heat conducted through the bearing material, on the hydrodynamic lubrication of a conical slide bearing. The study concerned various values of the heat conduction coefficient of the bearing material to investigate its influence on the temperature values of lubricating oil, and thus, on its viscosity, on the distribution of hydrodynamic pressure and on the calculated values of bearing load carrying capacities and friction forces.

Schlüsselwörter

  • slide bearing
  • hydrodynamic lubrication
  • conical bearing
  • heat conduction
  • pressure distribution
Uneingeschränkter Zugang

Diagnostic of Malfunction of Four Stroke Marine Engine Using Harmonic Components of Combustion Pressure Waveforms

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 97 - 103

Zusammenfassung

Abstract

The paper presents results of experimental measurements and analysis of combustion pressure and fuel pressure in high-pressure line before fuel valve. The aim of conducted experiments was detection of failures of high-pressure fuel system. Both pressure signals were recorded simultaneously and subsequently processed using FFT decomposition of obtained wavelets. The idea of comparison of both fuel and gas pressures came after observations of occurrence changes of wavelets form of fuel high pressure, probably caused by malfunction of injector’s sprayer. The engine from test bed is very well armoured with sensors, what enable observations of fuel and combustion pressure in real time. Unfortunately, such equipment is very unlike in real objects, what created un idea to find out whether run of combustion pressure wavelet reflects fuel pressure deviations and whether is possible to detect such kind of deviations in way of decomposition of indicated pressure wavelet. Experiment was carried out in laboratory of Gdynia Maritime University, using medium speed diesel engine. Simulation of malfunctions of fuel valve was obtained by installation of specially prepared spraying nozzles. All measurements were carried out at reference load of 75% of MCR (Maximum Continuous Rating). In order to get reliable results and avoid errors due to omitting outer atmospheric conditions, registrations were repeated several times, in days characterized by different temperature and atmospheric pressure.

Schlüsselwörter

  • technical diagnostics
  • marine engines
  • FFT
  • harmonic components
  • combustion pressure
Uneingeschränkter Zugang

Influence of Welding Parameters of FSW on Hardness Distribution in Joints of AW-5083 Alloy

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 105 - 112

Zusammenfassung

Abstract

The article presents the research results of hardness distribution of friction stir welded joint (FSW) of AW-5083 aluminium alloy. During the study used two types of tools: with cylindrical pin and with conical pin. FSW is a method of welding in the solid state, mechanical properties of joints welded by that method can be higher than that for arc welding techniques (MIG, TIG). The parameters of friction stir welding (FSW) used for joining 5083 alloy sheets were presented. Metallographic analysis of chosen joints showed the correct construction of structural bonded joints. The study was carried out using Vickers hardness HV1 in accordance with the requirements of the Polish Standard PN-EN 6507 using a hardness and microhardness-testing machine FM-800. The location of measurement points in the butt joint was determined in accordance with PN-EN 1043-1:2000. The indenter load was 9.8 N. In order to identify areas of particular characteristic of bonded joints macroscopic examination was performed using an optical microscope ZAISS AxioVert A1 MAT. The test specimens were polished and then etched with KELLER reagent. This enabled the precise identification of zones present in the joint, such as weld nugget, thermo-mechanically affected zone and native material. Hardness testing in across researched joints showed that the change of welding parameters in the range proposed in the research does not impact on the hardness distribution in the weld.

Schlüsselwörter

  • FSW
  • welding
  • hardness distribution
  • 5xxx aluminium alloy
  • shipbuilding
Uneingeschränkter Zugang

The Possibility of Application of the Acoustic Emission Method for Monitoring Friction Processes

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 113 - 119

Zusammenfassung

Abstract

This article presents the methodology and research results of monitoring friction processes between couple of cooperating elements by acoustic emission method. The research was carried out at the lathing machine test stand of the Technische Hochschule Mittelhessen. The test stand included lathing machine Proxon PD 210, shaft, made of austenitic stainless steel X2CrNi18-9 and steel plate, made of S235. The Friction process was monitored by an acoustic emission set made by Physical Acoustics Corporation (PAC). The PAC system includes: preamplifier USB AE Node, type 1283 with bandpass 20 kHz – 1 MHz, AE signal measurement sensor type VS 150M, with a frequency range 100-450 kHz, computer with AE Win for USB Version E5.30 software. During the study, the acoustic emission (AE) generated by friction between shaft and steel plate was recorded. The load of the plate was 0, 1, 2, 3, 4, 5 and 10 N. The following parameters were determined: amplitude, number of events – hits, the effective value of the signal (RMS). The use of grease between the cooperating elements caused a significant reduction in friction and thus the power of the generated signal (10 to 30 times). In the case of dry friction, without grease, the maximum RMS value was recorded at 4 N load and at the lubricant between the pair cooperating at 1 N load. The research has shown that it is possible to monitor the friction process between cooperating elements using the acoustic emission method.

Schlüsselwörter

  • Acoustic Emission (AE)
  • diagnostic
  • friction regimes
Uneingeschränkter Zugang

Impact of the Additives Used in Mineral Jet Fuels on the Lubricating Properties of Synthetic Fuels for Turbine Aircraft Engines

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 121 - 128

Zusammenfassung

Abstract

Hydrocarbon containing synthetic fuels represent a promising alternative fuels. Despite different chemical compositions, their properties should be similar to properties of mineral fuels, as they are designed for the same drive units. The basic parameter related to the protection of the adequate service life of the power supply devices, including precision pairs, is lubricity. Lubricity depends on a number of factors, including these related to the chemical composition of fuel components and operating additives introduced into fuels in order to modify their properties. The preliminary results of research on the effect of additives: lubricating, anti-corrosion and anti-electrostatic once, on the lubricating properties of a synthetic fuel are shown in the paper. It was observed that there are relations between the content of additives and the dynamics of film formation. It is significant that this does not apply only to the lubricating additive, but also the additive, which protects the correct electrostatic balance by providing sufficiently high electrical conductivity of the fuel. This may indicate that the formation of a lubricating film remains in relation to the intensity of energy transport from the lubricated surface to the molecules of lubricating additives inside the film. The results shown in the paper preliminary confirm the hypothesis, that synthetic components of fuels change the concentration of ordered molecular structures (which are present in mineral part of fuels and which can be responsible for energy transport inside the lubricating film), what resulted in worse fuel ability to create protective film, and anti-electrostatic additive improves lubricity of blends of synthetic and mineral components.

Schlüsselwörter

  • lubricity
  • fuels for turbine aircraft engines
  • synthetic components
  • additives
Uneingeschränkter Zugang

Computational Investigation of Compression Ratio and Bore Diameter Influence on Engine Performance and Knock Intensity

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 129 - 134

Zusammenfassung

Abstract

Processes of the combustion in combustion engines depend on cylinder bore and compression ratio. Compression ratio is a ratio of in-cylinder volume when piston is in bottom dead centre to volume when piston is in top dead centre. Theoretical engine efficiency is increasing together with compression ratio. However, in the real engine there are also other phenomena affecting the efficiency of the engine, which could results in lower performance of engine with higher compression ratio. This study presents knock intensity and performance gain in engine speed function of the 0D-1D engine model with different pistons set. Knock intensity is founded by implementing in combustion process knock sub-model based on Douaud and Eyzat induction time correlation using different pistons geometry. Examined engine model is air restricted Formula Student motorcycle engine. Mounted in intake system, air restrictor decreases knock intensity. Therefore, compression ratio could be increased. It was noticed that bigger bore diameter could reduce knock intensity. Researches realized that bigger bore size could cause performance drop at high rpm when flow is chocked. With changing of compression ratio, performance characteristic changes. Growing compression ratio decrease torque on low engine speed and increase on high engine speed. Further characteristic of the engine could be tuned by matching pistons with modified bore size and compression ratio.

Schlüsselwörter

  • simulation
  • combustion engines
  • compression ratio
  • motorsport
  • engine performance
  • knocks
Uneingeschränkter Zugang

Hydrogenization of Road Transport on the Example of Sweden, Poland and Japan

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 135 - 140

Zusammenfassung

Abstract

The article analyses the activities within the EU and national (Sweden, Poland) concerning the introduction of hydrogen fuel in road transport. The advantages and disadvantages of this drive were addressed. A directional program of hydrogen propulsion technology motion was presented on the example of Sweden and Poland. The most recent activities in Sweden regard the so-called Nordic Hydrogen Corridor European Project. The location of basic hydrogen refuelling stations in Poland until 2030 was proposed (HIT-2-Corridors European Project). These stations should be located in both TEN-T corridors running through Poland, i.e. in 1 – Poznan, 2 – Warsaw, 3 – Bialystok, 4 – Szczecin, 5 – the Lodz region, 6 – the Tri-City region, 7 – Wroclaw, 8 – the Katowice region, 9 – Krakow, to ensure the possibility of passing vehicles equipped with fuel cells (FCEV – Fuel Cell Electric Vehicle) among others between Western Europe and Scandinavia. For comparison, the article discusses FCEV development and initial hydrogen market creation in Japan. In the article is presented reasons for hydrogen society in Japan. The reasons are as follows: hydrogen is CO2 free; hydrogen can be produced from various sources, energy security – local production and consumption of energy, energy security – compensating for fluctuations in renewable energy production. In the article is presented Hydrogen/FCEV strategy Roadmap in Japan in context Hydrogen/FCEV Roadmap in China.

Schlüsselwörter

  • road transport
  • hydrogenization
  • combustion engines
  • environmental protection
Uneingeschränkter Zugang

Impact of the Type of Quench Aging after Hyperquenching on the Mechanical Strength Properties of AW-7020 Alloy

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 141 - 148

Zusammenfassung

Abstract

The article attempts to determine the influence of selected types of the heat treatment on the strength properties of the AW-7020 alloy used in the shipbuilding industry. The text presents information on the applied types of heat treatment. There are presented the results of the static tensile test of the material after its earlier hyperquenching and aging (natural and artificial) as well as comparison to the test results of the alloy without heat treatment. To illustrate the nature of the supersaturation and aging process, a test was carried out for a series of samples in a transitional state. During the tests for all the samples were determined: elongation at rupture and reduction of area at fracture, strength limit Rm and proof stress Re0.2. The results of the tests showed that the choice of the type of aging after saturation has significant importance for the strength properties of the AW-7020 alloy. It has been shown that it is possible to significantly accelerate the achievement of higher strength properties of the tested alloy, replacing the natural aging of the material with artificial aging.

Schlüsselwörter

  • AW-7020 alloy
  • age hardening
  • natural aging
  • artificial aging
  • hyperquenching strength limit
  • rupture elongation
  • fracture area reduction
  • intermediate state
  • age process hardening
Uneingeschränkter Zugang

The Impact of Methane Slip from Vessels on Environment

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 149 - 155

Zusammenfassung

Abstract

It was presented the ways of methane leakages during transport by sea. Due to greenhouse (GH), effect of carbon dioxide on atmosphere it was mentioned the carbon cycle on the Earth. Carbon dioxide is the main GH gas and it was indicated the change of concentration during last sixty years. It was increased about 30%. The possible methane leakages from vessels may increase the total GH effect due to high Global Warming Potential (GWP) of methane and other hydrocarbons. The carbon dioxide emission from engines is about 30% lower that from liquid marine fuels (diesel oils and heavy fuels). The liquefied natural gas (LNG) or compressed natural gas (CNG) seems to be a good ecological marine fuel. Due to methane leakages estimated on the level of 1-10% from mining to burning in the engines and the GWP on the level about 72-84 the look on methane as ecological fuel may change. It was calculated the equivalent effect (additional effect) of using methane as a marine fuel. Methane leakage on the level of 1-2.5% is equivalent to the same warming effect to the atmosphere as using popular marine diesel oils. Therefore, the leakage of methane during all operations should be as small as possible. In many cases, it is a serious problem for calculating the real leakages so they may be only estimated.

Schlüsselwörter

  • natural gas
  • methane slip
  • methane leakages
  • environment
  • impact on environment
Uneingeschränkter Zugang

Chosen Problems of Transport and Vessel’s Fuelling by Liquefied Natural Gas

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 157 - 162

Zusammenfassung

Abstract

It was presented the possibilities and ways of methane transport by sea. They are still searched new better possibilities of methane transport especially when the gas mining is at the sea. The advantages of using methane as marine fuel are discussed because it seems to be ecological and cheaper one. The lack of LNG bunkering network for vessels is the biggest problem to share methane as a marine fuel. Only a few ports inside the Baltic Sea area give such possibility. Of course, the network is under construction but the development goes too slowly to fulfil the International Maritime Organization (IMO) requirements on 2020 year. A challenge is to prevent failure during cargo operations, loading hose failure, pipe rupture, manifold leak, tank overflowing, or rupture etc. The risk of failure is increased due to very low temperature of liquid methane and the quick temperature change of all elements of cargo system during operations. The aim of the work was to show the indicated problems of vessel’s fuelling by LNG. It was discussed the methane slip during cargo operations and fuelling. The misfires during burning processes into the engines are the biggest problem due to very narrow window of methane self-ignition. It happens the misfiring or knocking cycles. It disturbs the correct work of the engine, resulting in quick engine malfunction or damage.

Schlüsselwörter

  • natural gas
  • LNG fuelled vessel
  • dual fuel engine
  • LNG
  • boil-off gas
Uneingeschränkter Zugang

Numerical Analysis of a Heat Transfer in Economizer Dedicated for 250 kW Power Solid Fuel Heating Boiler

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 163 - 168

Zusammenfassung

Abstract

Heating boilers, which are combusting solid fuels, are a very popular heating device in Poland. Heating boilers for solid fuels with nominal power equal to 250-300 kW reach a high level of waste heat. Polish companies produced a significant amount of heating boilers with that level of heating power, which are being exploited all the time in smaller companies and housing associations. A temperature of exhaust gases in the outlet of the heating boiler can be equal to 270-300ºC. It means that it is possible to recover some part of the waste heat. It can be realizable in an external heat exchanger. The article contains a methodology of a heat transfer process calculation for this type of heat exchangers. Estimated waste heat, which can be recovered from this installation, is equal to 25 kW. Additional heat exchanger implementation into a plant can increase an efficiency of solid fuel combustion process for a 10 percent. Construction of a heat exchanger was calculated during analytical calculations. After that, analytical calculations were verified in numerical calculations. Numerical analysis of a heat exchanger model was realized in the ANSYS Fluent environment. During calculations, a shell-and-tube heat exchanger construction was analysed. Authors of the article analysed a real temperature distribution for exhaust gases located on a shell side and for a water, which are located on a tube side of the economizer. Numerical calculations allowed to model conditions of economizer steady state work for a whole volume of this construction.

Schlüsselwörter

  • heating boiler
  • heat transfer
  • economizer
  • fluent
  • solid fuel
Uneingeschränkter Zugang

Analysis of Thermal and Mechanical Stresses of Renault Premium DXi11 460 Eev Four-Stroke Piston

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 169 - 175

Zusammenfassung

Abstract

In this article the engine piston Renault Premium DXi11 430 460 EEV has been analysed using the Finite Element Method. Analysis consider as well heat transfer phenomenon as the thermal and mechanical strains of the piston. Simulations were performed for the point of engine maximum power. Piston material was assumed to be 40HM (1.7225) steel and its properties are delivered basing on available scientific papers. The simulation assumed mean values of heat transfer coefficient, reference temperature and cycle pressure based on engine data, maximum power engine work simulation in AVL Boost software and literature. Part of boundary condition (e.g. cylinder wall temperature) was assumed basing on authors’ engineering intuition and experience. The resulting temperature distribution in the piston was implemented for geometrically nonlinear mechanical FEM analysis. Both the analysis of thermal stresses and stresses of the hot piston in the top dead centre were performed.

Schlüsselwörter

  • Heat transfer
  • temperature distribution
  • four-stroke engine piston
  • Finite Element Method
  • 1D combustion
Uneingeschränkter Zugang

Energetic Balance of Unmanned Ground Vehicle Hybrid Power Transmission

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 177 - 184

Zusammenfassung

Abstract

Article presents the energetic balance of small-unmanned vehicle hybrid power transmission. The vehicle equipped with series hybrid transmission consisted of electric engines connected to the battery pack and small Diesel power generator. In mentioned construction, battery is used as energy buffer and combustion engine is used more as emergency power supply, and is turned on when battery is depleted. In other condition, power generator can be turned off, without reducing power of transmission parameters, except its range. Investigation was divided on two stages. At first stage generator, charging unit and battery were placed outside the vehicle. One piston power generator was feed by Diesel fuel. Fuel consumption of power generator was recorded from AVL fuel balance and energy parameters were recorded by power line analyser of BMR Company. Generator was connected to the direct current power plant. 70 Ah and 48 DC Lithium-polymer battery was charged from the power plant. After charging cycle, small water resistor was used to discharge the battery. Power parameters of discharged battery were measured. This enable to measure balance form tank to the battery. Second stage of the energetic balance determination was to measure internal resistances of vehicle power transmission from current inverter/converter connected to the engine and through the transmission up to the wheels of the vehicle. Power loss of energy at different speed of vehicle wheels without ground contact was measured in respect of power consumption. The series hybrid transmission is consider less efficient than parallel but because of specific configuration of power transmission, it was possible to reach higher efficiency.

Schlüsselwörter

  • balance
  • unmanned vehicle
  • hybrid transmission
  • test stand
Uneingeschränkter Zugang

Experimental Research on Influence of the Fuel Nozzle Geometry on the Fuel Consumption of the Marine 4-Stroke Diesel Engine

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 185 - 190

Zusammenfassung

Abstract

The article presents experimental research that has been carried out on a marine, 4-stroke, 3-cylinder, turbocharged engine. During testing, the engine operated at a constant rotational speed of 750 rpm and a load from 0 kW to 280 kW. The engine was fuelled by diesel oil of known specification and loaded by electric generator with water resistance. The fuel consumption was measured during the engine operation with fuel nozzles with different geometries. The measurement of the fuel consumption was carried out using a weighing system that was designed, constructed, and manufactured by the “KAIZEN” scientific research team at the Faculty of Mechanical Engineering at the Gdynia Maritime University. The results of measurements show changes in the fuel consumption by the engine with the geometry of the injected fuel spray. The research facility is Sulzer’s 3-cylinder, 4-stroke, turbocharged AL25/30 piston engine. The fuel system consists of Bosch injection pumps controlled by a rotation speed regulator. Fuel injectors are centrally located in the cylinder heads of the engine.

Schlüsselwörter

  • marine engine
  • fuel consumption
  • fuel injection
  • experimental measurements
  • compression ignition engine
Uneingeschränkter Zugang

Analysis of Selected Simulated Failure of a Reciprocating Compressor Using Computer Diagnostic System

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 191 - 198

Zusammenfassung

Abstract

In the article, the problems of selected failures that may occur during operation of positive displacement compressors and possible reasons for their occurrence were described. It also included methods for checking performance and diagnostics, with particular emphasis on research using an electronic indicator. Possible mechanical damages of air compressors for various applications have also been characterized. Non-destructive diagnostic methods were described to detect and diagnose damage, taking into account their suitability and limitations in their application. In the further part of the article selected tests results of air compressor, specially adapted to simulation of failures were presented. The test stand has been equipped with sensors for measuring the pressure and temperature of the compressed gas and the sensor of the angular position of the compressor shaft, allowing examining the impact of damage on compressor working parameters. The result of the research was to compare the compressor indicator diagrams in the operational condition, with the simulated failure, and between different failures and to learn the changes of processes taking place inside the cylinder during the compressor’s work cycle. All the test results could be observed in real time, besides the diagnostic software, supporting the tests, made it possible to record measurements. In the described software, it is possible to compare the courses for different cases, to then make a comparative analysis of the results obtained in the state of functional and simulated disability.

Schlüsselwörter

  • piston compressor
  • test stand
  • diagnostic system
  • simulated malfunctions
Uneingeschränkter Zugang

The Usage of a Thermoclimatic Chamber for Technoclimatic Tests of Special Vehicles and Mobile Machines

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 199 - 206

Zusammenfassung

Abstract

Constantly increasing technical and operational demands are set for modern manned and unmanned special vehicles, all − terrain vehicles, and mobile machines. Their producers must comply with very restrictive standards, strict legal regulations, and high customer requirements. They concern not only functionality and efficiency of described objects, but also resistance to the impact of environmental and climatic exposure. Vehicles and mobile machines must be adapted to work in different climatic conditions such as low and high temperature, variable humidity, wind, dustiness, rainfall, variable atmospheric pressure, solar radiation. Verification of the correctness of operation of all these systems installed in machines, vehicles and engineering units requires experimental research in specified and stable climatic conditions. These special conditions can only be implemented in a thermoclimatic chamber. Thanks to these researches, it is possible to confirm the effectiveness of solutions that allow machines to work in extreme climatic conditions, as well as to detect a number of defects and imperfections of the structure, unpredictable at the design stage. The article describes the research procedure certified by Polish Centre for Accreditation and discusses examples of technoclimatic research carried out recently in the thermoclimatic chamber of Laboratory of Technoclimatic Research and Heavy Duty Machines of Cracow University of Technology.

Schlüsselwörter

  • environmental and climatic exposure
  • extreme climatic conditions
  • technoclimatic research
  • thermoclimatic chamber
  • accredited test procedure
Uneingeschränkter Zugang

Stress Distribution in an Anisotropic Beam Subjected to Load

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 207 - 214

Zusammenfassung

Abstract

The article presents the physical equations describing the isotropic and anisotropic materials. Orthotropic material and monotropic are special varieties of anisotropy. Constructional steel, pine wood and polyester-glass composite were tested. The beams were made from these materials. The beams were subjected to external loads. The external load caused internal forces in beams. Calculations of stress distribution were carried out by finite element method (Patran – Nastran software). The calculation results allowed for precise illustrate the distribution of stress especially in layered materials. The load is basically a transmitted through the strong layers of composite. This is illustrated in the figures. Wood is materials of a layered structure and is classified as inhomogeneous materials. Whereas steel is considered as a homogeneous material. Passing from the level of microscopic inhomogeneity to the macroscopic homogeneous level is called homogenization. This method formulates the macroscopic description by homogenizing microscopic properties. For the purpose of mathematical description of a material, the real centre can be substituted by a homogeneous centre. The homogenization method is commonly used to describe the properties of rocks, wood, composites, reinforced concrete, as well as human osseous tissues. The description of the mechanical properties of isotropic materials is based on the theory of elasticity, while the anisotropic materials are based on the anisotropic theory of elasticity. Calculations of anisotropic materials are quite complicated (large number of physical quantities) and sometimes-approximate results are obtained.

Schlüsselwörter

  • isotropic material
  • anisotropic material
  • beam deflection
  • stress distribution in the beam
Uneingeschränkter Zugang

Finishing Treatment of Marine Pump Shafts Made of X5CrNi18-10 Steel

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 215 - 222

Zusammenfassung

Abstract

One of the greatest problems of modern production techniques is the achievement of an appropriate quality at minimal costs and accompanied by the production efficiency increase. Therefore, while designing the production process, the technology used should have a considerable influence on the durability and reliability of machine parts to be produced. During finish treatment, the final dimensions as well as functional properties are imparted to a given element by application of proper treatment type. The engineer has a range of production techniques to choose for the proper surface layer formation. It is crucial to find a suitable solution which will meet the requirements as well as the work conditions of a given machine part. The article presents the results of influence of cutting parameters change on temperature and cutting forces during turning process of stainless steel. A shaft made of 304L stainless steel was used for the research. The cutting process was carried out on a universal CDS 6250 BX-1000 centre lathe. Measurement of cutting forces during lathing process used DKM 2010 turning dynamometer. The turning process was conducted by a cutting tool with CCET09T302R-MF insert by DIJET. During the turning, the following machining parameters were used: cutting speed Vc = 152, 219, 304 m/min, feed f = 0.044, 0.062, 0.083 mm/rev and cutting depth ap = 0.4, 0.8, 1.2, 1.6 mm. The view of the nose radius of cutting tool before and after the turning process was made by the Smartzoom 5 microscope.

Schlüsselwörter

  • turning dynamometer
  • temperature and cutting forces
  • stainless steel
Uneingeschränkter Zugang

A Stochastic Model of Changes in the Operational States of Means of Transport

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 223 - 230

Zusammenfassung

Abstract

In the article, application of a Markov process for modelling the process of transport means operational state changes whose duration times can be estimated by Erlang distribution is presented. The research object is a system of city bus transport operation, used in a selected agglomeration. A homogenous Markov process was assumed a mathematical model of the process of transport means operation. Transformation of a stochastic process, for which distributions of random variables denoting duration times of the states are Erlang distributions, into a stochastic process characterized by exponential distribution of the state duration times, was performed at the costs of the state space extension. The use of a homogeneous Markov process for mathematical modelling of the operation process was dictated by the fact that the process reflects adequately, from the point of view of the research goal, the real operation process. In order to illustrate the process, a hypothetical, simplified calculation example was provided. Reliability of technical objects needs to be maintained at appropriate level, which is the responsibility of the repair and maintenance subsystem ensuring. This subsystem consists of two subsystems. The main tasks of the mobile emergency teams include providing vehicles, that is, buses that are outside the depot with the serviceability state as quickly as possible or hauling damaged buses to technical service stations.

Schlüsselwörter

  • homogeneous Markov process
  • operation process
  • operational state
  • transport means
Uneingeschränkter Zugang

Thermal Barrier Concepts Against Continuous Laser Irradiation

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 231 - 238

Zusammenfassung

Abstract

Rapid development in the high-power laser technology poses new requirements on the thermal protective materials. Military laser applications have been characterized and the examples have been presented. Existing materials, which may be used as a protection against high-energy laser beam, have been discussed. Several concepts of the new thermal barrier materials have been proposed. The proposals include multilayer structures, porous materials, systems with phase change materials (PCMs), and systems with various thermal contact resistance for different contact pairs. Comparative study based on numerical simulation results has been performed to assess efficiency of each proposal.

Three major candidate technologies were considered: the CO2 laser, the HF/DF chemical laser, and the Nd-glass solid-state laser. The CO2 combustion driven gas laser was built in mid-seventies. Its power was 500 kW with the poor beam quality. In the context of thermal protection against laser, high conductive material component in a complex structure might be especially useful, since irradiated surface is usually limited to a small size.

Schlüsselwörter

  • laser weapons
  • thermal barriers
  • multilayer structures
  • phase-change process
  • thermal contact resistance
Uneingeschränkter Zugang

Analysis of Selected Operating Parameters of Engine Powered by a Mixture of Biocomponents and Diesel Oil

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 239 - 244

Zusammenfassung

Abstract

Reaching of high parameters of a drive unit and low pollution of the natural environment is considered to be the most desired effect of motorization. The use of the additive in the form of fatty acid methyl esters to the diesel oil, assumes lowering of harmful fuel gases’ emission and reaching high operating parameters of an engine, such as power and turning moment. Studies on the power output and the turning moment of an engine with self-ignition are presented in the study. The subject matter of the studies was a combustion engine with self-ignition of the power of 80 kW with the direct common rail system and turbo-compressor’s supercharging and with electromagnetic injectors. The tested engine was powered with diesel oil and the mixture of fatty acid methyl esters and the diesel fuel, in proportions 10%, 30% and 50% with an improver, at the standard settings of the fuel injection controllers. The vehicle used for the testing purposes, has been singled out with respect to the specific features, such as: universality of its use as a means of transportation and the opportunity of modification of the injection parameters, resistance to possible unfavourable consequences resulting from the use of the fuel mixture. The studies were conducted on a chassis test house, at full engine’s loading. The vehicle placed on the test house’s rollers, was strapped with belts to the foundation, and then accelerated up to the specific speed and subjected to loading standing in place. In such a manner, the road conditions were simulated. The obtained results of the tests were subject to the statistical analysis. From their analysis it results, that application of the mixture lowers the engine’s parameters to a degree unnoticeable at the time of its operation.

Schlüsselwörter

  • transport
  • means of transport
  • diesel oil
  • biocomponent
  • alternative fuels
Uneingeschränkter Zugang

Motor Vehicle Diagnostics in Military Units

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 245 - 252

Zusammenfassung

Abstract

Transport pertains to all functional areas of the State’s activities on every administrative level. Road transport is a very important branch of global economy and constitutes a part of the logistics network. It pertains to the transportation of cargo, items, and people. Cooperation between the branches of civilian transportation and military logistics must be the focus of continuous improvement efforts. Enhancements in this respect can serve to avoid possible failures and disruptions. The quality and availability of infrastructure plays a significant role, not only with respect to civilian, but also military assets. The condition of the vehicle is important for the safety of road transport. The provision of transport services in a military unit should mainly rely on military-civilian cooperation and effective communications. The condition of the means of transportation has been indicated as a factor influencing transport safety. Employing new technology and solutions enables constant improvements to the diagnostic system, broadening the knowledge and enhancing the skills of the motor vehicle driver in terms of proficiency in operating and maintaining the vehicle used.

Schlüsselwörter

  • motor vehicle diagnostics
  • vehicle operation
  • vehicle condition
  • military-civilian cooperation
  • transportation support
Uneingeschränkter Zugang

Comparative Analysis of the Calculation Methods of the Marine Propeller’s Blade Thickness

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 253 - 260

Zusammenfassung

Abstract

Strength of the propellers with the skewback greater than 25º has to be numerically analysed according to marine classification societies. The finite element method (FEM) is advised for that kind of calculations. Classical and typical propellers (skewback < 25º) may be designed on the base of empirical equations given by the societies. The minimal thickness of the propeller blade is determined by the equations. Each classification society has their own empirical formula. Sometimes, well-designed propeller for one society has not enough strength according to the other society. What is more, propellers designed according to the empirical formulas might be not optimal. Comparative analysis of the marine propeller’s blade strength has been described in the article. Calculations of the propeller’s blade thickness have been done by two international classification societies’ empirical formulas (ABS and DNV). The results have been compared with Finite Element Method calculations (NASTRAN program). The methodology of propeller static strength vibration analyses is presented. Numerical calculation methodology is based on solid-state mechanics with loadings determined by fluid mechanics calculations. Steady state and transient fluid flow of the propeller’s working conditions were taken into account. In order to determine the optimal modelling method of the propeller several different numerical models were compared, including free model of whole propeller and single blade with boundary conditions placed in the foot. The propeller optimization was the main target of the analyses. Propeller blade thickness might be reduced after FEM method analysis - the propeller mass saving can be achieved.

Schlüsselwörter

  • marine propeller
  • strength
  • vibration
  • solid structure in fluid
  • FEM modelling methodology
Uneingeschränkter Zugang

Spectrofluorimetry of Chosen Distillates of Oil after Pyrolysis of Scrap Tires

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 261 - 268

Zusammenfassung

Abstract

One of way to obtain liquid hydrocarbons can be pyrolysis of scrap tires. The hydrocarbon substances produced by this method may be an addition to traditional fuels, i.e. gasolines or fuels for diesel engines. In laboratory conditions at Department of Mechatronics of University of Warmia and Mazury there were obtained pyrolytic products and prepared three distillates related to temperatures 160, 204 and 350ºC. Analyses of shapes of fluorescence spectra were carried out in Department of Physics of Gdynia Maritime University. Spectra of fluorescence were prepared applying the spectrofluorimeter Hitachi F-7000 FL, which allows applying of excitation wavelength from 200 nm until 600 nm, whereas analysing of emitted, can be performed until 750 nm. In here reported study excitation and emission range for the most intense fluorescence are presented. There were prepared four solutions of pyrolytic products in the n-hexane: 4 ppm, 20 ppm, 100 ppm and 500 ppm. In order to show dependence of intensity fluorescence and shapes of excitation-emission spectra on type of distillate and concentration both kind of visualization – three-dimensional and as contour maps – are shown in this article. In analysed range of wavelengths, intensity of fluorescence grows with concentration of oil, whereas structure of the shape of spectra simplify when concentration increases. The presented effects associated with the fluorescence of pyrolysis products allow to predict the possibility of developing a method for determining the content of these substances in mixtures with petroleum refining products and other liquid hydrocarbons.

Schlüsselwörter

  • fuels
  • used car tires
  • pyrolysis
  • fluorescence
  • excitation-emission spectra
Uneingeschränkter Zugang

Properties of a Three Disc Cycloid Gear as a Result of Bench Test

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 269 - 280

Zusammenfassung

Abstract

The most common design solution are cycloidal gearboxes with two discs, in which the reaction forces of bearings from the working discs create a bending moment on the high-speed input shaft, additionally affecting bearings. In the article are presented the results of tests of the cycloid gear prototype with three discs. Instead of the second disc, the introduction of two side discs, 1800 from the centre disc, allows you to reduce this moment to zero. To compensate for the unbalance of the shaft, the side discs have half the width of the centre disc. Each disc works with its own, separate set of bronze rollers, separated by Teflon washers, which should reduce the friction forces. In the article are presented the results of the tests of the cycloid gear prototype determining basic parameters such as efficiency, torque fluctuations on the input and output shaft, housing vibrations in three directions. FFT analysis of registered parameters showed high compliance of the designated frequencies for different measured signals. The assumed advantages, i.e. high efficiency and low vibration level in the tested range, were confirmed. The results are presented in the form of three-dimensional graphs as functions of speed and torque. High efficiency (80-90) % was obtained for load moments above 150 Nm, which is practically independent of the rotational speed with which the cycloid gearing works. The oil temperature during the tests was maintained in the range of 36°C ± 2°C. The maximal torque of the cycloidal gear was 500 Nm.

Schlüsselwörter

  • cycloidal gear
  • efficiency
  • vibrations
Uneingeschränkter Zugang

E-REV’s Hybrid Vehicle Range Modeling

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 281 - 286

Zusammenfassung

Abstract

Article presents the influence of battery capacity and electric generator power on a series hybrid vehicle range. Vehicles equipped with increased battery capacity and small power generator are special type of series hybrid vehicles called Extended Range Electric Vehicles – E-REV. The increasing number of hybrid and electric vehicles increases the demand for durable and efficient sources of energy storage for vehicles.

The hybrid vehicle’s battery driven range is increased as battery power density is increased and its cost is decreased. This is due to the battery cell cost decreasing and improvement of cell chemistry. That cause higher and higher distance driven on electric mode in hybrid vehicles. First series hybrid vehicle engine power was equal to engine powered the vehicle’s wheels. Nowadays, series hybrid vehicles are more electric vehicles with small power generator (piston or turbine engine. In such a constructions, battery is used as an energy buffer and combustion engine is used more as emergency power supply.

To minimize this phenomenon, manufacturers use counteracting solutions that include mounting additional cells in the battery that are switched on when the battery controller identifies a particular battery cell’s failure or high degradation. This is due to the deep and shallow discharges of the battery, the numbers of charging and discharging cycles, and the age and technology of battery packs.

AMESim software was used for the simulation of the E-REV hybrid vehicle range. The research was based on modelling the range of the vehicle with different battery capacity works with power generator of different power. By modelling different capacity of battery and power of small generator, it is possible to determine the vehicle range.

Schlüsselwörter

  • battery
  • simulation model
  • electric vehicle
  • E-REV
Uneingeschränkter Zugang

Potential of Biomass-to-Fuel Conversion Technologies for Power and Means of Transport

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 287 - 294

Zusammenfassung

Abstract

Reduction of CO2 emissions in Poland (excluding transport) should be related to a change in the structure of electricity production sources. Similar actions have been taken by many European countries. In 2017, in the European Union’s power industry, the largest emitters were dominated by coal-fired power plants in Germany (seven power plants). However, the leader of this ranking turned out to be the Belchatów power plant owned by the Polish Energy Group (PGE). Renewable energy is energy obtained from natural processes. It should be obtained in a way that would not cause a deficit of natural resources (renewed in a short time) to have a limited impact on the environment. The purpose of promoting and using renewable energy sources (RES) is to reduce the harmful effects of energy on the natural environment, primarily by limiting greenhouse gas emissions (water vapour, CO2, CH4, CFC, N2O, halon, ozone and industrial gases HFC, PFC, SF6). Biomass is the most widely used renewable energy source currently used. The study of the literature and comparison of the set parameters for different types of biomass in the given order shows that Virginia mallow has the highest usefulness for energy purposes. Considering the fact that both cashew and coconut (shells) cannot be grown due to the climate prevailing in Poland, Virginia mallow seems to be the best alternative for traditional fuels used in the energy sector in the analysed group. Virginia mallow has competitive properties to wood biomass and hard coal only significantly supercedes in terms of calorific value. The energy properties of Virginia mallow can additionally be improved as a result of the torrefaction process. In addition, in the literature on the subject, attention is paid to the fact that mallow may be grown on less-favoured soils and the process of its collection – in contrast to other such plants – does not require the use of specialized agricultural machinery.

Schlüsselwörter

  • renewable energy sources
  • biomass
  • sida hermaphrodita
  • torrefaction
  • renewable fuel
Uneingeschränkter Zugang

The Effect of the Addition of Nanotubes Upon the Thermo-Protective Properties of the Aramid-Reinforced Composite

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 295 - 301

Zusammenfassung

Abstract

The aim of this article is to present findings concerning the thermo-protective research into ablative materials. The authors analysed the impact of the addition of carbon nanotubes upon the selected ablation properties, i.e. the ablation mass waste, average linear rate of ablation and the backside temperature of the specimens. The performed tests as well as the obtained findings allowed formulating a number of conclusions, which are useful in creating future composites.

Composition of individual test samples; ablation testing; average relative ablation mass loss, depending on the volume share of carbon nanotubes; average ablation rate, depending on the volume share of carbon nanotubes; temperature of the rear surface of the insulating sample, depending on the volume share of carbon nanotubes; temperature inside the composite, depending on the volume share of carbon nanotubes; comparison of the temperature of ablation surface, temperature inside the composite and temperature on the rear surface of the wall of carbon nanotubes after the exposition to a heat flux are presented in the article.

Schlüsselwörter

  • ablative materials
  • composites
  • thermal resistance
  • ablation properties
Uneingeschränkter Zugang

Evaluating Combustion, Performance and Emission Characteristics of CI Engine Operating on Diesel Fuel Enriched with HHO Gas

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 303 - 311

Zusammenfassung

Abstract

Research of efficient and ecological parameters was carried out with compression ignition (CI) engine using diesel fuel and additionally supplied hydrogen and oxygen (HHO) gas mixture. HHO gas is produced by electrolysis when the water was dissociating. At constant engine’s brake torque and with increasing HHO gas volumetric concentration in taken air up to 0.2%, engine efficient indicators varies marginally, however, with bigger HHO concentration these parameters becomes worse. HHO increases smokiness, but it decreases NOx concentration in exhaust gas. Numerical analysis of combustion process using AVL BOOST software lets to conclude that hydrogen, which is found in HHO gas, ignites faster than diesel fuel and air mixture. Hydrogen combustion before TDC makes a negative work and it changes diesel fuel combustion process – diesel ignition delay phase becomes shorter, kinetic (premixed) combustion phase intensity gets smaller.

Schlüsselwörter

  • CI engine
  • HHO gas
  • engine efficiency
  • emission
Uneingeschränkter Zugang

Diagnostics and Analysis of Jet Engine Malfunctions

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 313 - 318

Zusammenfassung

Abstract

The article describes emergency situations occurring in the propulsion system of an aircraft with the jet engine used in Poland on planes such as MiG-29 or F-16. The article also presents statistics of polish aircrafts damage over the years. Due to the technological progress of turbine engines used in fighter aircraft, the authors decided to discuss the issue of monitoring emergency states in this study. In particular, efforts have been made to ensure that damage to the aircraft engine can be prevented by monitoring its operation with the equipment available on the aircraft. Counteracting phenomena that occur in the jet engine can lead to permanent damage; can lead to an increase in the safety of the pilot and the local population, but also to a reduction of costs. The authors also decided to se the threats that occur during take-off and landing, and the flight when they land outside the plane. Jet engines are almost reliable and most common cause of engine damages as the analysis shows are foreign bodies, particularly dangerous for a turbine engine on or near the runway, as well as birds, which provides to mechanical damage of engine. Securing the airport against foreign objects on the runway is one of the most important tasks of ground staff.

Schlüsselwörter

  • jet engine
  • aircraft
  • diagnostics
  • safety
Uneingeschränkter Zugang

Use and Calibration of 5-Hole Pressure Probes to Measurement of Airflow Velocity

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 319 - 327

Zusammenfassung

Abstract

Multi-hole probes are simple and robust device to measurement of flow velocity magnitude and direction in wide range of angles of attack – up to 75°. They become popular as they may be easily use to measurement of unknown flow velocity, while optical methods, like PIV or LDA, require some knowledge about the flow for proper setting of measurement devices. Multi-hole probes are also more lasting in comparison with CTA hot-wire probes, which may be damaged by a dust.

A multi-hole probe measures air pressure with one pressure tap on its tip and a few (usually 2, 4, 6 or more) taps on conical or semispherical surface of the probe tip. Based on measured pressures, some non-dimensional pressure coefficients are calculated, which are related to flow velocity direction (i.e. two angles in Cartesian or spherical coordinate system) and magnitude. Finding relations between these parameters is relatively complex, which for years was limiting application of multi-hole probes.

The article summarizes methods of multi-hole probes calibration and use, which may be classified as nulling and non-nulling methods or – with other criteria – as global and local methods. The probe, which was presented in the article, was the 5-hole straight probe manufactured by Vectoflow GmbH and calibrated in the stand designed and manufactured at the Institute of Aviation. The local interpolation algorithm has been used for calibration, with some modifications aimed on mitigate of mounting uncertainty, which is related with the non-alignment of flow velocity direction and probe axis

Results of calibration showed that the accuracy of presented methodology is satisfactory. The standard measurement uncertainty was assessed for 0.2° for the pitch angle and yaw angle, which is better than accuracy declared by the probe’s manufacturer (1.0°). The measurement uncertainty of the flow velocity is approximately 0.12 m/s, similarly like in manufacturer’s data.

Schlüsselwörter

  • aerodynamic measurement
  • turbomachinery
  • measuring devices
  • flow direction measurement
  • multi-hole probes
Uneingeschränkter Zugang

Adaptive Landing Gear Control System Assumptions

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 329 - 333

Zusammenfassung

Abstract

In the present time, landing energy dissipation process in aviation shock absorber design is optimized for the most demanding, but still safe, landing scenario (reserve energy landing conditions). Most of the current solutions are based on a fixed hole (orifice) or a set of holes regulating hydraulic fluid flow in the shock absorber. This approach although safe provides no optimization of the forces acting on the fuselage in different (less energetic than limit energy) conditions. Due to the progress in hydraulic flow control, it is possible to design and control a proper system for extended optimization of the landing process energy dissipation. The complete system contains two parts, one of which is a direct flow executive electro-mechanical system and second of which is an electronic control system. The electronic control system directly manages executive system via a set of inputs, thus creating proper output signals for the optimal flow control.

In this article, the author presents the idea of the computer control part of the adaptive hydraulic flow control system. The author describes a set of possible control input and output signals both external and internal, from the landing gear reference system, characterizing their role in the landing process. The author also defines possible control algorithms selected to fit the assumptions of the adaptive landing gear system. Finally, the author presents a proposal for the laboratory grade control system for future testing of the assumptions described in this article.

Schlüsselwörter

  • laboratory testing
  • landing gear
  • adaptive control
  • control system
Uneingeschränkter Zugang

Strain Gauge Pin Based Force Measurement

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 335 - 340

Zusammenfassung

Abstract

In this article authors present force measurement method based on strain gauge measuring system installed inside pin, which is a part of light helicopter Main Landing Gear Shock Absorber. Strain gauges in full bridge configuration were installed inside the mounting pin (upper one – fuselage side). Placement and type of strain gauges were selected during the preliminary tests, which verified the validity and conditions of the force measurement. Preliminary tests allowed verification and selection of an optimal measurement system by testing two types of them. The impact on force according to the angle of force vector direction was also verified. Preliminary tests of the strain gauges equipped pin were performed using quasistatic tests stand – 40 T hydraulic press for applying force acting on shock absorber and pin. Whole measuring system is planned to be used in real time analysis of shock absorber force acting on fuselage mounting node.

The strain gauges allows measurement of force in any place of the structure, the article presents the advantages of the system located inside pin. Additionally, the installation technologies of strain gauges in hard-to-reach places are presented. The article is summed up with an analysis of the problems, which arise during the installation and measurement process using strain gauges installed in such a specific place.

Schlüsselwörter

  • strain gauges
  • landing gear
  • test stand
  • measuring system
Uneingeschränkter Zugang

Performance Requirements and Simulation of Rotor Operation for High-Mountain Rescue Helicopter

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 341 - 348

Zusammenfassung

Abstract

Simulation results concerning performance of helicopter suitable for high-mountain rescue operations are presented. Including operations in regions of the highest Himalaya Mountains, the possibility of hover ceiling out of ground effect (OGE) at 10,000 m above sea level is assumed. Demand of high ratio of developed lift to power required for hover leads to choice the coaxial rotor configuration as the best for rescue helicopter, which can operate in extremely high mountain environment, and gives good stability features in wind gust conditions in comparison with single main rotor helicopter. For performance calculations the simple model of helicopter is applied, which consists of fuselage point mass and rotor disk. The cases of partial and total power loss are considered to define range of H-V zones and possibilities of flight continuation due to height of landing surface over level of sea. The rotor blades and rotor loads are calculated applying detail model of elastic blade, which includes effects of its deflections due to out-of-plane bending, in plane bending, and torsion. The Runge-Kutta method is applied to solve equations of motion of rotor blades with taken into account effects of blade pitch control and variable deflections of blades. According to Galerkin method, the blade parameters of motion are treated as a combination of torsion and bending eigen modes of the rotor blades. Elastic blade model allows defining behaviour rotor blades in selected states of flight: hover, level flight, wind gust conditions, and pull-up manoeuvre. The results of simulation for upper and lower rotor for blade deflections and loads are shown in form of time-run plots and rotor disk distributions. The simulation investigation may be applied to define features of helicopter configuration suitable for operation in extremely high mountain conditions.

Schlüsselwörter

  • rescue helicopter
  • high-mountain operations
  • rotor blade deformation
Uneingeschränkter Zugang

The Effect of Using the Kline-Fogleman Modification Upon the Coefficient Characteristics of Aerodynamic Forces in the Airfoil

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 349 - 356

Zusammenfassung

Abstract

The wing is the main aircraft construction element, whose main task is to produce the lift, balancing the aircraft weight as well as ensuring the execution of all flight states for which the aircraft was designed. The selection of appropriate airfoils or the development of new ones is one of the most important constructions goals. As a rule, constructors aim at ensuring a sufficiently large lift with little aerodynamic drag in order to increase the scope of utility angles of attack and such shaping of these characteristics so that the aircraft performance, close to the critical angles of attack, guarantees an adequate level of safety. One of the methods of improving the aerodynamic properties of airfoils is the Kline-Fogleman modification. It involves an application of a step into the airfoil contour at a place. It enforces the creation of a swirling air stream, preventing the separation and maintaining airflow over the profile and thus the reduction of drags, as well as delaying separation. The use of this type of a solution is justified when designing unmanned aerial vehicles, of small sizes, which move with slow speeds and sometimes-large angles of attack, including those close to critical angels of attack. The Kline-Fogleman modification decreases the likelihood of aircraft stalling.

The aim of this work is to present an analysis of airflow over NACA0012 airfoil with Kline-Fogleman modification. The calculations were made by solving the problem of numerical fluid mechanics. For calculations, the Comsol Maribor programme was used. The investigation focused on several different airfoil modifications (KFm-1, KFm-2, KFm-3). This enabled a selection of a solution, providing the most desirable aerodynamic characteristics.

Schlüsselwörter

  • airfoil
  • CFD
  • aerodynamics characteristics
  • Kline-Fogleman modification
  • NACA0012 airfoil
Uneingeschränkter Zugang

Time – Frequency Dynamic Characteristics 2D in the Quality Assessment of Welded Joints

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 357 - 361

Zusammenfassung

Abstract

The authors of the article have been looking for a new parameters and dynamic characteristics, which can be applied to non-destructive testing of welded joints. All characteristics have been based on recorded data generated during the vibration tests of welded joints with and without failures. The article deals with the methods of assessing welding joints using 2D: time – frequency dynamic characteristics. A calculation procedure used for analysing simultaneous changes of the response modules, registered by acceleration sensors was presented. Vibrations amplitudes were transformed to a function of time and frequency (simultaneously) and presented over 2D time – frequency characteristics. The analyses of the characteristics were performed for a plate without any welded joint, for a plate with non-defected welded joint and for a plate with a welded joint defected by an edge bonding. Having analysed registered 2D time – frequency dynamic characteristics it can be noticed that presenting the responses analysed simultaneously over the time and frequency allows evaluating if examined system maintains non-linearity and, at the same time, it allows to indirectly assess the quality of the welded joint. The proposed measure parameters of the quality of a welded joint can be defined as a dispersion of colours on the obtained characteristics. The faults (and the vibration nonlinearity) of the welded joints is bigger if the dispersion is greater.

Schlüsselwörter

  • welding
  • welded joints
  • non-destructive testing
  • NDT
  • SHM
  • vibrations
  • time – frequency characteristics
Uneingeschränkter Zugang

Comparison of the Environmental Impacts of a Plug-in Hybrid and a Full Electric Car Using Life Cycle Assessment

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 363 - 369

Zusammenfassung

Abstract

Full electric (FEV) and plug-in hybrid (PHEV) vehicles are promising, forward-looking technologies to reduce greenhouse gas (GHG) emissions and other pollution related to road transport. The powertrain of a FEV is composed of a battery, control electronics and the electric motors. A PHEV has much lower battery capacity but it contains an extra internal combustion engine and gearbox. Many argue that FEVs are more energy-efficient than internal combustion engines. However, this energy needs to be stored in heavy, large-capacity battery packs that require plenty of energy and resources to produce as well as highly polluting rare earth elements mining. In this article, an environmental comparison of FEVs and PHEVs is shown using life cycle assessment (LCA). To make the comparison realistic, two models similar in size and power have been selected: Volkswagen E-Golf FEV and Volkswagen GTE PHEV.

Results show that the production of FEVs need more energy and it means more burden on the environment however during the use phase it causes less emissions. Since the local electricity production mix and, in case of PHEVs, the user behaviour highly affects the results, three different countries (Hungary, Poland and Norway) and two different use types are considered. The quantified environmental footprints as well as the break-even distances are presented. Sensitivity of the results towards the assumed conditions during the whole design lifetime of the vehicles is discussed.

Schlüsselwörter

  • full electric vehicle
  • plug-in hybrid electric vehicle
  • life-cycle assessment
Uneingeschränkter Zugang

Analysis of the Use of OBD II / EOBD Congestion Diagnostics in the Light of Vehicles Operation and their Technical Condition

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 371 - 378

Zusammenfassung

Abstract

Transport in human life has played a key role since ancient times. At the turn of years it has evolved, initially using only the power of human legs, then the animals until use internal combustion engines. The first internal combustion engine was presented by Brackenburow in 1836. The construction showed a very desirable type of combustion engine – burning a mixture of hydrogen and oxygen and expelling clean water as exhaust gas. However, the invention was abandoned due to its innovativeness and lack of trust in it. The topic was again taken in 1860 presenting a two-stroke engine using a mixture of natural gas and air with spark ignition. Striving for even greater perfection, Rudolf Diesel in 1893 presented and patented the first self-ignition diesel engine. The first solution, although used today, has shown that automotive engines leave a significant margin of reliability.

The operational reliability of internal combustion engines is important in relation to the conditions of their operation and technical condition. The impact of toxic substances in exhaust gases and their impact on the natural environment these days is an important issue.

One of the forms of work on the problem is the current diagnosis of engine operation. This was possible thanks to the use of the OBD I system, which was later transformed into OBD II / EOBD and the result of the test results obtained to the applicable EURO standards. The system allows testing during a road test in normal car operation. Using the OBD recorder, the operation of an example vehicle will be analysed in various operating conditions, and the obtained results will provide diagnostic possibilities.

Schlüsselwörter

  • on-board diagnostics
  • diagnostic procedures
  • OBD
  • OBD II
  • EOBD
  • reliability of engines
  • operation of engines
Uneingeschränkter Zugang

Multidimensional Simulation of Combustion and Knock Onset in Gas Engines

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 379 - 389

Zusammenfassung

Abstract

Natural gas fuelled internal combustion engines enable efficient energy conversion with relatively low environmental impact. Depending on the specific application, the available fuel quality, and the emission regulations to be fulfilled, different types of gas-engine combustion systems are in use. The major performance and hence efficiency limiting factors in gas fuelled engines are related to the lower ignitability of natural gas at part load and the appearance of abnormal combustion (knock) at high load conditions. This article provides an overview of the multidimensional CFD simulation workflow for the investigation and assessment of flame propagation and knock onset characteristics in different types of natural gas fuelled internal combustion engines. The most common approaches for simulating flame propagation/combustion under engine conditions are presented together with selected models for describing the pre-flame reactions finally leading to knock onset in the unburned in-cylinder charge ahead of the flame. Based on selected application examples, the models’ performance and capabilities with respect to reflecting the essential characteristics of flame propagation and knock onset are presented.

Schlüsselwörter

  • gas engines
  • simulation
  • combustion
  • efficiency
  • knock onset
Uneingeschränkter Zugang

Combustion of Mixture of Diesel Fuel with Gasoline in a Compression Ignition Engine

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 391 - 398

Zusammenfassung

Abstract

Paper presents results of experimental investigation of combustion process of diesel-gasoline blend in compression ignition direct injection engine. The researches were conducted for constant load of engine at constant rotational speed. Operating parameters of engine powered with diesel-gasoline blend were at the same level as for engine powered by pure diesel fuel. The preliminary study was conducted using CFD modelling. Based on encouraging modelling results preliminary experimental research was carried out. It turned out that it is possible to co-burning diesel with the gasoline as a blend. A mixture of 20, 40 and 60% of gasoline with diesel was used. It was concluded that an increase in gasoline fraction in blend causes delay of start of the combustion process. The homogeneity of the fuel-air mixture was improved due to longer ignition delay, which is accompanied by higher values of pressure rise rate. With 20 and 40% of gasoline fraction causes higher peak pressure compared to reference fuel-burning ware obtained. Up to 40% of gasoline fraction, the BSFC was kept at the same level as for reference fuel. It was observed that with the increase in gasoline fraction up to 40% NOx emission increased as well. Based on the carried out tests it can be stated that it is possible to co-burn gasoline with diesel in a compression ignition engine while maintaining the invariable engine operating parameters and exhaust emissions.

Schlüsselwörter

  • combustion
  • engine
  • diesel
  • gasoline
  • combustion phases
Uneingeschränkter Zugang

Method for Estimating the Static Friction Degree in the Slide Pair of the Miniaturised Electrohydraulic Servomechanism

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 399 - 407

Zusammenfassung

Abstract

One of the most important parameters specifying the usability of the miniaturised electrohydraulic servomechanism includes a static friction degree in its slide pairs, i.e. resistance of the slider’s movement from rest after some time of its staying at rest under pressure. Therefore, at the stage of designing and construction of the electrohydraulic servomechanism, it is important to determine the greatest static friction degree, which may arise in the slider hydraulic pair of this device during its operation. The objective of this article is to present a method for estimating the maximum static friction values in the slide pair based on the extreme value theory. The operation and loading conditions of the slide pair of the electrohydraulic servomechanism for the unmanned aircraft control system were described. The procedure for estimating the maximum static friction degree in the slide pair with the use of the extreme and probabilistic grid was presented. The extreme and probabilistic grid structure was based on the Gumbel probability graph. The graphic presentation of results of the static friction experimental studies in the slide pair on the extreme and probabilistic grid was discussed. By using the graphics method, the empirical dependence of the static friction force in the slide pair on the working fluid pressure in the hydraulic drive (loading conditions) was determined. A practical example of estimating the maximum values of the static friction force that may occur in the slider hydraulic pair of the miniaturized electrohydraulic servomechanism is shown.

Schlüsselwörter

  • operation
  • hydraulic drive
  • electrohydraulic servomechanism
  • pressure
  • friction force
Uneingeschränkter Zugang

The Influence of the Blades Leading Edge Anti-Erosion Protection on Main Rotor Performances

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 409 - 414

Zusammenfassung

Abstract

This article presents the influence of rotor blade airfoil shape on main rotor performances. In this case, we analysed the influence of anti-erosion tape, which is applied to the leading edge of the blade to protect the blades from environmental conditions. In Gyro-Tech Innovation an Aviation Company and Institute of Aviation the independent tests of helicopter and gyroplane main rotors were performed. Research includes: bench tests, on the test stand for dynamic testing of insulated rotors and tests on two flying constructions, gyroplane Cavalon produced by AutoGyro GmbH Company and ultralight helicopter Dynali H3. On the test bench, a two-blade rotor, used in ultralight and unmanned helicopters, was tested. In article, the authors present importance of the proper selection and application of anti-erosion coatings on rotor blades. Discuss the behaviour of the above-mentioned constructions with main rotor blades leading edge covered anti-erosion tape, during flight tests. The results of bench tests, including the comparison of polar curves of the main rotor with anti-erosion coating and without were also presented and discussed.

In the summary of this article among others the solution of technological pocked introduced in the rotor blade, corresponding to the thickness of the anti-erosion tapes, in such way that after tape is applied it does not change the contour of the blade airfoil were presented.

Schlüsselwörter

  • airfoil
  • rotor blades
  • flight tests
  • light and ultra-light rotorcrafts
Uneingeschränkter Zugang

Detailed Modelling of the Internal Processes of an Injector for Common Rail Systems

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 415 - 426

Zusammenfassung

Abstract

In the last few decades exhaust emissions of road vehicles have decreased dramatically, owing to the more and more stringent emission standards issued by the legislative bodies of different countries, combined with the necessity of cleaner, better performing vehicles from society side. The introduction of Common Rail (CR) injection systems has been a great step towards achieving this target, thanks to its flexibility in fuel injection pressure, timing, and length, along variable engine load conditions. However, it is highly time and resource consuming to set up the injection system for all operating points of different engines, moreover, as the injection is a small scale, high speed process, the behaviour of the internal processes is challenging to measure. The best solution for these problems is to create a detailed model of the injector, where all the hydraulic, mechanic, and electromagnetic subsystems are represented, this way the internal working conditions can be analysed and resources can be saved.

In this work, a detailed model of a first generation CR injector for commercial vehicles is presented and validated against needle lift data. The fluid dynamic and mechanic sub-systems are presented in details to thoroughly investigate the working principles of the injector internal parts. The fluid dynamic subsystem contains the chambers, holes, and throttles of the injector, while the mechanic subsystem models the motion and behaviour of the internal parts. The main features of the injector internal working conditions are described and analysed. Apart from the needle lift, these included solenoid anchor, pin and control piston lifts, the control chamber pressure and the mechanical force acting on the anchor. Five test cases were chosen on a medium duty test engine to represent a wide range of operation points from full load to idle and the simulated results were compared to the measured data. The simulated control piston movement accurately matched the measured curves in every test case.

Schlüsselwörter

  • Common Rail
  • injector
  • simulation
  • modelling
  • internal combustion engines
53 Artikel
Uneingeschränkter Zugang

Manoeuvring Characteristics of the Push Train with an Auxiliary Steering Device

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 7 - 13

Zusammenfassung

Abstract

The carried out and planned studies on the revitalisation of Odra and Vistula rivers in Poland and restoration of regular inland navigation put a great attention into environmental issues related to the operation of inland waterborne transport means. The design and operational parameters of inland ships and convoys are dependent on waterways dimensions and their influence on the environment. The article presents problems related to manoeuvring performance of the push train, which is the most popular inland waterborne means of freight transport in Poland and in Europe. The alternative auxiliary steering device improving push train manoeuvrability has been tested on the physical model of a push barge. The active bow steering device consisted two bow rotors has the influence on the operational safety of the push train with respect to improved manoeuvring characteristics and decreased impact on the environment, port and lock facilities, ships and boats in narrow passages. The results of model tests presented in the article allowed for estimation of turning ability of the push train with and without bow rotors. A significant difference was observed with respect to the manoeuvring area, distances of advance, tactical diameter, and time of the manoeuvre.

Schlüsselwörter

  • inland push train manoeuvrability
  • manoeuvrability criteria
  • bow rotor
Uneingeschränkter Zugang

The Magnetic Field Curvature Correction Algorithm Dedicated for Helmet Mounted Cueing Systems

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 15 - 30

Zusammenfassung

Abstract

The article presents the new built in Poland helmet mounted cueing system NSC-1 Orion with a magnetic method, dedicated to the multi-purpose helicopters W-3PL Gluszec. This system uses the magnetic field generated by the system of three mutually orthogonal electric coils. The principle of operation of this system is described and the method of determining the angular position of the pilot’s helmet relative to the helicopter’s cabin using the reference magnetic field and the directional cosines matrix are discussed. Electrical flat coils, constructed in the Polish Air Force Institute of Technology (AFIT), generating a magnetic field with curved symmetry axis characteristics, causing errors in determining the angular position of the pilot’s helmet are shown. As a way to minimize these errors, an original proprietary algorithm for correcting the negative impact of the magnetic field curvature generated by the on-board system has been presented. Mathematical relations describing the presented correction process as well as selected results of simulation and experimental investigations in the area of inaccuracy of the “before” and “after” systems of applying the developed algorithm were given. Inaccuracies determined from computer simulations of the developed mathematical relations were compared with experimental data from magnetic field measurements using the integrated three-axis sensor ADIS-16405, used in the laboratory of the AFIT Avionics Division for helmet control of the angular position of the moving observation and sighting head and reflector-search light.

Schlüsselwörter

  • transport
  • avionics
  • helmet-mounted cueing systems
  • errors of the angular positioning
  • magnetic field measurement
  • flat coil profile modelling
Uneingeschränkter Zugang

Vegetable Oils as Additives to Improve the Lubricity of Low-Sulphur Fuels

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 31 - 36

Zusammenfassung

Abstract

The aim of the study was to determine the sulphur content in 33 samples of oils pressed from different species of vegetable. The unconventional oil samples were purchased from commercial store. Oils was analysed in terms of sulphur content according to the method using X-ray fluorescence spectrometry with wave dispersion, that is described in the PN-EN ISO 20884, 2012 standard. Obtained results of sulphur analysis were presented as the arithmetic mean ± standard deviation (from three replicates) and statistically analysed using the Statistica 13.0 PL program. In order to indicate significance of differences between oils analysis of variance (ANOVA) with Tukey’s test of p ≤ 0.05 significance level was used. The statistical analysis indicated significant differences in the content of sulphur content in the analysed vegetable oils, which could affect the lubricity of prepared fuel blends and in some cases significantly, increase the sulphur content above acceptable value 10 ppm. It was concluded that vegetable oils could be a suitable raw material improving the lubricating properties of low-sulphur diesel oils. However, due to significant differences in the sulphur content in the analysed samples, the content of this element should be analysed beforehand in order to eliminate the possibility of exceeding the permissible level of sulphur in transport fuels.

Schlüsselwörter

  • sulphur content
  • different species
  • vegetable oils
  • biofuel production
  • lubricity
Uneingeschränkter Zugang

Review of Loss Models for High Pressure Turbines

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 37 - 44

Zusammenfassung

Abstract

This article presents a literature review about the physical analysis of the loss models, which are used in off-design procedure for high-pressure turbines.

A high-pressure turbine is designed to have maximum performance at design point. However, engines are operating in different conditions, and the comprehension of off-design conditions is very important. The loss mechanisms are very complex and predictions considering empirical methods are a good approach to have preliminary results. Based on these results, different researches have proposed theories about the loss mechanisms, and over the time, these models have been modified to describe better the phenomena involved between blades and flow. Once the physical mechanisms behind the loss models are known, it is possible to compare them and understand the reason why the results given for some methods present a higher agreement to experimental or numerical data.

In this framework, 2D numerical simulations of the flow around the blades of an axial high pressure turbine with different off design conditions have been realized, by using ANSYS FLUENT® code, to show the losses described by some of these models. Using these simulations a loss model has been selected and implemented in Matlab® to compare its results with the experimental data found in literature.

Schlüsselwörter

  • turbomachinery
  • gas turbines
  • high-pressure turbine
  • HPT
  • loss models
Uneingeschränkter Zugang

The Impact of Unevenness and Instability of Flue Gas Temperature on the Technical Condition of Gas Turbine Blades

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 45 - 51

Zusammenfassung

Abstract

Gas turbines are used in the power sector, aviation, pump houses, and other technical systems. Such a broad range of application is associated with favourable indicators: high power, rather low weight per unit of power, significant efficiency, as well as high durability. All of these indicators greatly depend on the combustion chamber flue gas temperature. It is important for the flue gas temperature to be uniform around the turbine perimeter and stable over time. This condition is extremely important also in the case of frequent temperature variations associated, e.g. with a variable operating range of a manoeuvre aircraft turbojet engine. The paper analyses the causes for the unevenness and instability of combustion chamber flue gas temperature. The impact of the fuel quality, the technical condition of the fuel supply system, as well as the operating conditions of the combustion chamber-turbine assembly was shown. The issues regarding the presence of various types of damage to turbine elements, their blades in particular, were defined. The main cause behind the damage is the unevenness and instability of flue gas temperature, resulting in the presence of overheating, creeping, thermal fatigue, high-temperature corrosion of blade material. The forms of that damage, especially the first turbine stages, were presented. Blade material microstructure test results showed increased layer thickness, grain-size, and especially, adverse modification of the strengthening γ’ phase in the temperature function. It was concluded periodic diagnostics of turbine blades with the optical method enables the non-invasive evaluation of their technical condition and drawing conclusions in terms of their durability.

Schlüsselwörter

  • flue gas temperature
  • gas turbine
  • blade
  • diagnostics
  • technical condition
Uneingeschränkter Zugang

Analysis of Operating States of Haul Trucks Used in Surface Mining

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 53 - 58

Zusammenfassung

Abstract

Mining transport system based on the use of haul trucks should result from thorough analysis of technical and operating issues – which can have a crucial impact on the cost of minerals extraction. This selection should consider hitherto disregarded criteria, such as technical infallibility, operating parameters like mean operating time between failures (MTBF), mean failure intensity and fault modes and effect analysis etc. Considering the above issues, the following article is an attempt to analyse operating parameters of transport fleet of haul trucks for mineral resource in surface mining. Diagram of the typology of technical and operational haul truck states; source: own study; mean failure intensity graph and mean failure intensity graph for the total observation time; relationships between mean expected time between consecutive failures of specific object and (MTBF) mean value of the time, in which specific equipment is in the down time due to a failure are presented in the article. The MTBF index is a basic parameter helpful to determine dependability and can be used for logistic planning, in particular in the field of spare parts. This index allows determining the cost of object use throughout its entire life cycle.

Schlüsselwörter

  • surface mining
  • haul truck
  • fault modes and effect analysis
  • operating states
Uneingeschränkter Zugang

The Preliminary Research of the Influence of Grease Microcontainers Made on the Surface of the Slide Association on the Vibration Signal Recorded for this Association

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 59 - 67

Zusammenfassung

Abstract

There is shown the construction of an elaborated test stand for the test research of sliding friction associations. The following properties of tested friction associations are described: type (chemical composition) and hardening of applied materials, as well as the results of the analysis of topography of their collaborating surfaces (base material and then after creating grease microcontainers in it). The methodology and the range of performed researches are described. The researches were conducted using the accelerometer A0760GP and the industrial measurement device Emerson CSI 2130. On the basis of recorded vibration signals, their amplitude spectra were determined. These spectra were being compared and analysed in reference to the possibilities of application of measurements of vibration signals to indication of the process of association wear. It was found that the process of wear of the tested sliding association without lubrication from grease microcontainers is visible as the change of form of vibration signals recorded for this association as even over-a-dozen-fold changes in the value of amplitudes of some special harmonic components of those signals, especially high-frequency components within the analysed range of frequencies. It was also found that the application of the grease microcontainers on the surface on which rollers slide (not roll) allowed to acquire a significant reduction of the process of wear of the tested slide association, showed by the slower pace of growth of the value of all harmonic components, especially high-frequency components within the analysed range of frequencies. At the end there were provided directions of further researches.

Schlüsselwörter

  • vibration
  • slide association
  • friction
  • wear
  • grease microcontainers
Uneingeschränkter Zugang

Deviation Angle Models in off-Design High-Pressure Turbines

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 69 - 74

Zusammenfassung

Abstract

In the article, a set of deviation angle models, which are used to predict the off-design performance high-pressure turbines, has been presented, basing on a literature study. The deviation angle is a deviation between the actual flow angle and the blade inclination angle. It is an essential parameter in turbine performance evaluation. This angle shall be obtained accurately in 1-D design and evaluation, so as to ensure the validity of blade profiling and calculation results. If deviation angle is ignored, the turbine will produce a lower change of tangential velocity, and consequently a lower torque, output work and enthalpy drop than intended by the designer. For this reason, the deviation angle model needs to be established. There exist a number of different deviation models, resulting in varying degrees of flow deviation when applied. In the article, correlations for gas outlet angle, dependent on the Mach number at outlet and determined by the blade loading towards the trailing edge has been presented. The main difficulty in establishing the deviation model is a continuity in defining the angle for all speed ranges (both subcritical and supercritical). Each of the models presented in the article deals with this problem in a different way. A few deviation models, briefly discussed in the article, are based on experimental data and one is based on analytical approach.

Schlüsselwörter

  • turbomachinery
  • gas turbines
  • high-pressure turbine
  • HPT
  • deviation angle
Uneingeschränkter Zugang

Estimating the Main Dimensions of the Ship’s Hull

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 76 - 80

Zusammenfassung

Abstract

Preliminary ship owner’s assumptions for new ship consist of deadweight, speed-shipping line and others. Taking it as a base, in early stage of design one has to select propulsion type. This goal needs definition of principal dimensions of a vessel, which are the base for further calculations of hull’s resistance and evaluation of necessary power of main engine to fulfil shipping requirements. Selection of main dimensions of vessel is limited by rules regarding buoyancy, stability, hull strength, manoeuvring capability, and limitations related to seaways or harbours characteristic. In this article is presented the methodology of calculation of principal parameters of a vessel, necessary for calculation of displacement in relation to vessel’s type, volumetric coefficients, Froude number, and others values affecting ship’s dimensions. It is about midship section coefficient, waterline coefficient, prismatic coefficient. Those values are necessary for calculation of hull resistance. In the article, are presented major constraints for designing of new vessels coming from ship-owner assumptions such as seafaring limitations. In the table is presented comparison of results of calculations above-mentioned values of three type of vessels representing same displacement. There are also presented different calculation methods of transverse midship section coefficient and wet area coefficient, for 3 types of vessels (container vessel, bulk carrier and tanker with displacement of 120000 t.

Schlüsselwörter

  • seagoing ships
  • hull coefficient
  • hull dimensions parameters
Uneingeschränkter Zugang

Numerical Simulations of a Bird Strike Against a Helicopter Windshield

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 81 - 88

Zusammenfassung

Abstract

The article presents simulation results of a bird strike with a helicopter windshield of small helicopter category. It turns out that there are no certification requirements regarding windshield of this category. Therefore Agusta A109 helicopter as a representing this helicopter category has been chosen for researcher. The simulations were conducted on the basis of LS-DYNA software by means of the SPH method for bird model shape of cylinder with hemispherical endings for the speed of Vc = 285 km/h. The analyses regarded various angles of the bird model impact into windshield. As a result of the simulations, comparative analyses in the aspect of time curves of the kinetic energy, velocity, and windshield deformation were achieved. The analysis shows that at smaller angles of attack, the bird’s model has a higher speed at the moment of impact, and thus greater kinetic energy, because it did not lose speed as a result of the collision. In addition, the deflection of the windshield is smaller. In some cases, the deflection of the windshield may be observed, which indicates the elastic response of the system. In case of impact in the normal direction to the surface of the glass, the bird’s model practically pierces it. The use of a thicker pane translates into less deformation of the pane, but causes its destruction at the connection point with the helicopter carrier structure.

Schlüsselwörter

  • bird strikes
  • helicopter windshield
  • numerical analyses
  • LS-DYNA
Uneingeschränkter Zugang

Numerical Analysis of Influence of Bearing Material Thermal Conductivity Coefficient on Hydrodynamic Lubrication of a Conical Slide Bearing

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 89 - 96

Zusammenfassung

Abstract

One of the main parameters affecting the hydrodynamic lubrication of slide bearings is the viscosity of lubricating oil. Many studies show, that significant changes in the viscosity of oil occur along with changes in its temperature. The influence on the temperature distribution in the lubrication gap of the slide bearing have a variety of factors, and one of them is the amount of heat exchanged between the lubricant and the environment. The temperature of the lubricating oil of operating bearing is usually higher than the ambient temperature. In addition to the convection, which occurs during the flow (heat exchange related to the oil supply and discharge system) some amount of heat is transferred to the bearing sleeve material (and also to the bearing shaft), and then it is conducted to sleeve outer surface. The amount of heat transferred through the bearing sleeve is mainly dependent on the difference of temperatures between inner and outer sleeve surfaces and also depend on the heat conduction coefficient of sleeve material. This article presents the results of modelling of the influence of amount of heat conducted through the bearing material, on the hydrodynamic lubrication of a conical slide bearing. The study concerned various values of the heat conduction coefficient of the bearing material to investigate its influence on the temperature values of lubricating oil, and thus, on its viscosity, on the distribution of hydrodynamic pressure and on the calculated values of bearing load carrying capacities and friction forces.

Schlüsselwörter

  • slide bearing
  • hydrodynamic lubrication
  • conical bearing
  • heat conduction
  • pressure distribution
Uneingeschränkter Zugang

Diagnostic of Malfunction of Four Stroke Marine Engine Using Harmonic Components of Combustion Pressure Waveforms

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 97 - 103

Zusammenfassung

Abstract

The paper presents results of experimental measurements and analysis of combustion pressure and fuel pressure in high-pressure line before fuel valve. The aim of conducted experiments was detection of failures of high-pressure fuel system. Both pressure signals were recorded simultaneously and subsequently processed using FFT decomposition of obtained wavelets. The idea of comparison of both fuel and gas pressures came after observations of occurrence changes of wavelets form of fuel high pressure, probably caused by malfunction of injector’s sprayer. The engine from test bed is very well armoured with sensors, what enable observations of fuel and combustion pressure in real time. Unfortunately, such equipment is very unlike in real objects, what created un idea to find out whether run of combustion pressure wavelet reflects fuel pressure deviations and whether is possible to detect such kind of deviations in way of decomposition of indicated pressure wavelet. Experiment was carried out in laboratory of Gdynia Maritime University, using medium speed diesel engine. Simulation of malfunctions of fuel valve was obtained by installation of specially prepared spraying nozzles. All measurements were carried out at reference load of 75% of MCR (Maximum Continuous Rating). In order to get reliable results and avoid errors due to omitting outer atmospheric conditions, registrations were repeated several times, in days characterized by different temperature and atmospheric pressure.

Schlüsselwörter

  • technical diagnostics
  • marine engines
  • FFT
  • harmonic components
  • combustion pressure
Uneingeschränkter Zugang

Influence of Welding Parameters of FSW on Hardness Distribution in Joints of AW-5083 Alloy

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 105 - 112

Zusammenfassung

Abstract

The article presents the research results of hardness distribution of friction stir welded joint (FSW) of AW-5083 aluminium alloy. During the study used two types of tools: with cylindrical pin and with conical pin. FSW is a method of welding in the solid state, mechanical properties of joints welded by that method can be higher than that for arc welding techniques (MIG, TIG). The parameters of friction stir welding (FSW) used for joining 5083 alloy sheets were presented. Metallographic analysis of chosen joints showed the correct construction of structural bonded joints. The study was carried out using Vickers hardness HV1 in accordance with the requirements of the Polish Standard PN-EN 6507 using a hardness and microhardness-testing machine FM-800. The location of measurement points in the butt joint was determined in accordance with PN-EN 1043-1:2000. The indenter load was 9.8 N. In order to identify areas of particular characteristic of bonded joints macroscopic examination was performed using an optical microscope ZAISS AxioVert A1 MAT. The test specimens were polished and then etched with KELLER reagent. This enabled the precise identification of zones present in the joint, such as weld nugget, thermo-mechanically affected zone and native material. Hardness testing in across researched joints showed that the change of welding parameters in the range proposed in the research does not impact on the hardness distribution in the weld.

Schlüsselwörter

  • FSW
  • welding
  • hardness distribution
  • 5xxx aluminium alloy
  • shipbuilding
Uneingeschränkter Zugang

The Possibility of Application of the Acoustic Emission Method for Monitoring Friction Processes

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 113 - 119

Zusammenfassung

Abstract

This article presents the methodology and research results of monitoring friction processes between couple of cooperating elements by acoustic emission method. The research was carried out at the lathing machine test stand of the Technische Hochschule Mittelhessen. The test stand included lathing machine Proxon PD 210, shaft, made of austenitic stainless steel X2CrNi18-9 and steel plate, made of S235. The Friction process was monitored by an acoustic emission set made by Physical Acoustics Corporation (PAC). The PAC system includes: preamplifier USB AE Node, type 1283 with bandpass 20 kHz – 1 MHz, AE signal measurement sensor type VS 150M, with a frequency range 100-450 kHz, computer with AE Win for USB Version E5.30 software. During the study, the acoustic emission (AE) generated by friction between shaft and steel plate was recorded. The load of the plate was 0, 1, 2, 3, 4, 5 and 10 N. The following parameters were determined: amplitude, number of events – hits, the effective value of the signal (RMS). The use of grease between the cooperating elements caused a significant reduction in friction and thus the power of the generated signal (10 to 30 times). In the case of dry friction, without grease, the maximum RMS value was recorded at 4 N load and at the lubricant between the pair cooperating at 1 N load. The research has shown that it is possible to monitor the friction process between cooperating elements using the acoustic emission method.

Schlüsselwörter

  • Acoustic Emission (AE)
  • diagnostic
  • friction regimes
Uneingeschränkter Zugang

Impact of the Additives Used in Mineral Jet Fuels on the Lubricating Properties of Synthetic Fuels for Turbine Aircraft Engines

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 121 - 128

Zusammenfassung

Abstract

Hydrocarbon containing synthetic fuels represent a promising alternative fuels. Despite different chemical compositions, their properties should be similar to properties of mineral fuels, as they are designed for the same drive units. The basic parameter related to the protection of the adequate service life of the power supply devices, including precision pairs, is lubricity. Lubricity depends on a number of factors, including these related to the chemical composition of fuel components and operating additives introduced into fuels in order to modify their properties. The preliminary results of research on the effect of additives: lubricating, anti-corrosion and anti-electrostatic once, on the lubricating properties of a synthetic fuel are shown in the paper. It was observed that there are relations between the content of additives and the dynamics of film formation. It is significant that this does not apply only to the lubricating additive, but also the additive, which protects the correct electrostatic balance by providing sufficiently high electrical conductivity of the fuel. This may indicate that the formation of a lubricating film remains in relation to the intensity of energy transport from the lubricated surface to the molecules of lubricating additives inside the film. The results shown in the paper preliminary confirm the hypothesis, that synthetic components of fuels change the concentration of ordered molecular structures (which are present in mineral part of fuels and which can be responsible for energy transport inside the lubricating film), what resulted in worse fuel ability to create protective film, and anti-electrostatic additive improves lubricity of blends of synthetic and mineral components.

Schlüsselwörter

  • lubricity
  • fuels for turbine aircraft engines
  • synthetic components
  • additives
Uneingeschränkter Zugang

Computational Investigation of Compression Ratio and Bore Diameter Influence on Engine Performance and Knock Intensity

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 129 - 134

Zusammenfassung

Abstract

Processes of the combustion in combustion engines depend on cylinder bore and compression ratio. Compression ratio is a ratio of in-cylinder volume when piston is in bottom dead centre to volume when piston is in top dead centre. Theoretical engine efficiency is increasing together with compression ratio. However, in the real engine there are also other phenomena affecting the efficiency of the engine, which could results in lower performance of engine with higher compression ratio. This study presents knock intensity and performance gain in engine speed function of the 0D-1D engine model with different pistons set. Knock intensity is founded by implementing in combustion process knock sub-model based on Douaud and Eyzat induction time correlation using different pistons geometry. Examined engine model is air restricted Formula Student motorcycle engine. Mounted in intake system, air restrictor decreases knock intensity. Therefore, compression ratio could be increased. It was noticed that bigger bore diameter could reduce knock intensity. Researches realized that bigger bore size could cause performance drop at high rpm when flow is chocked. With changing of compression ratio, performance characteristic changes. Growing compression ratio decrease torque on low engine speed and increase on high engine speed. Further characteristic of the engine could be tuned by matching pistons with modified bore size and compression ratio.

Schlüsselwörter

  • simulation
  • combustion engines
  • compression ratio
  • motorsport
  • engine performance
  • knocks
Uneingeschränkter Zugang

Hydrogenization of Road Transport on the Example of Sweden, Poland and Japan

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 135 - 140

Zusammenfassung

Abstract

The article analyses the activities within the EU and national (Sweden, Poland) concerning the introduction of hydrogen fuel in road transport. The advantages and disadvantages of this drive were addressed. A directional program of hydrogen propulsion technology motion was presented on the example of Sweden and Poland. The most recent activities in Sweden regard the so-called Nordic Hydrogen Corridor European Project. The location of basic hydrogen refuelling stations in Poland until 2030 was proposed (HIT-2-Corridors European Project). These stations should be located in both TEN-T corridors running through Poland, i.e. in 1 – Poznan, 2 – Warsaw, 3 – Bialystok, 4 – Szczecin, 5 – the Lodz region, 6 – the Tri-City region, 7 – Wroclaw, 8 – the Katowice region, 9 – Krakow, to ensure the possibility of passing vehicles equipped with fuel cells (FCEV – Fuel Cell Electric Vehicle) among others between Western Europe and Scandinavia. For comparison, the article discusses FCEV development and initial hydrogen market creation in Japan. In the article is presented reasons for hydrogen society in Japan. The reasons are as follows: hydrogen is CO2 free; hydrogen can be produced from various sources, energy security – local production and consumption of energy, energy security – compensating for fluctuations in renewable energy production. In the article is presented Hydrogen/FCEV strategy Roadmap in Japan in context Hydrogen/FCEV Roadmap in China.

Schlüsselwörter

  • road transport
  • hydrogenization
  • combustion engines
  • environmental protection
Uneingeschränkter Zugang

Impact of the Type of Quench Aging after Hyperquenching on the Mechanical Strength Properties of AW-7020 Alloy

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 141 - 148

Zusammenfassung

Abstract

The article attempts to determine the influence of selected types of the heat treatment on the strength properties of the AW-7020 alloy used in the shipbuilding industry. The text presents information on the applied types of heat treatment. There are presented the results of the static tensile test of the material after its earlier hyperquenching and aging (natural and artificial) as well as comparison to the test results of the alloy without heat treatment. To illustrate the nature of the supersaturation and aging process, a test was carried out for a series of samples in a transitional state. During the tests for all the samples were determined: elongation at rupture and reduction of area at fracture, strength limit Rm and proof stress Re0.2. The results of the tests showed that the choice of the type of aging after saturation has significant importance for the strength properties of the AW-7020 alloy. It has been shown that it is possible to significantly accelerate the achievement of higher strength properties of the tested alloy, replacing the natural aging of the material with artificial aging.

Schlüsselwörter

  • AW-7020 alloy
  • age hardening
  • natural aging
  • artificial aging
  • hyperquenching strength limit
  • rupture elongation
  • fracture area reduction
  • intermediate state
  • age process hardening
Uneingeschränkter Zugang

The Impact of Methane Slip from Vessels on Environment

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 149 - 155

Zusammenfassung

Abstract

It was presented the ways of methane leakages during transport by sea. Due to greenhouse (GH), effect of carbon dioxide on atmosphere it was mentioned the carbon cycle on the Earth. Carbon dioxide is the main GH gas and it was indicated the change of concentration during last sixty years. It was increased about 30%. The possible methane leakages from vessels may increase the total GH effect due to high Global Warming Potential (GWP) of methane and other hydrocarbons. The carbon dioxide emission from engines is about 30% lower that from liquid marine fuels (diesel oils and heavy fuels). The liquefied natural gas (LNG) or compressed natural gas (CNG) seems to be a good ecological marine fuel. Due to methane leakages estimated on the level of 1-10% from mining to burning in the engines and the GWP on the level about 72-84 the look on methane as ecological fuel may change. It was calculated the equivalent effect (additional effect) of using methane as a marine fuel. Methane leakage on the level of 1-2.5% is equivalent to the same warming effect to the atmosphere as using popular marine diesel oils. Therefore, the leakage of methane during all operations should be as small as possible. In many cases, it is a serious problem for calculating the real leakages so they may be only estimated.

Schlüsselwörter

  • natural gas
  • methane slip
  • methane leakages
  • environment
  • impact on environment
Uneingeschränkter Zugang

Chosen Problems of Transport and Vessel’s Fuelling by Liquefied Natural Gas

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 157 - 162

Zusammenfassung

Abstract

It was presented the possibilities and ways of methane transport by sea. They are still searched new better possibilities of methane transport especially when the gas mining is at the sea. The advantages of using methane as marine fuel are discussed because it seems to be ecological and cheaper one. The lack of LNG bunkering network for vessels is the biggest problem to share methane as a marine fuel. Only a few ports inside the Baltic Sea area give such possibility. Of course, the network is under construction but the development goes too slowly to fulfil the International Maritime Organization (IMO) requirements on 2020 year. A challenge is to prevent failure during cargo operations, loading hose failure, pipe rupture, manifold leak, tank overflowing, or rupture etc. The risk of failure is increased due to very low temperature of liquid methane and the quick temperature change of all elements of cargo system during operations. The aim of the work was to show the indicated problems of vessel’s fuelling by LNG. It was discussed the methane slip during cargo operations and fuelling. The misfires during burning processes into the engines are the biggest problem due to very narrow window of methane self-ignition. It happens the misfiring or knocking cycles. It disturbs the correct work of the engine, resulting in quick engine malfunction or damage.

Schlüsselwörter

  • natural gas
  • LNG fuelled vessel
  • dual fuel engine
  • LNG
  • boil-off gas
Uneingeschränkter Zugang

Numerical Analysis of a Heat Transfer in Economizer Dedicated for 250 kW Power Solid Fuel Heating Boiler

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 163 - 168

Zusammenfassung

Abstract

Heating boilers, which are combusting solid fuels, are a very popular heating device in Poland. Heating boilers for solid fuels with nominal power equal to 250-300 kW reach a high level of waste heat. Polish companies produced a significant amount of heating boilers with that level of heating power, which are being exploited all the time in smaller companies and housing associations. A temperature of exhaust gases in the outlet of the heating boiler can be equal to 270-300ºC. It means that it is possible to recover some part of the waste heat. It can be realizable in an external heat exchanger. The article contains a methodology of a heat transfer process calculation for this type of heat exchangers. Estimated waste heat, which can be recovered from this installation, is equal to 25 kW. Additional heat exchanger implementation into a plant can increase an efficiency of solid fuel combustion process for a 10 percent. Construction of a heat exchanger was calculated during analytical calculations. After that, analytical calculations were verified in numerical calculations. Numerical analysis of a heat exchanger model was realized in the ANSYS Fluent environment. During calculations, a shell-and-tube heat exchanger construction was analysed. Authors of the article analysed a real temperature distribution for exhaust gases located on a shell side and for a water, which are located on a tube side of the economizer. Numerical calculations allowed to model conditions of economizer steady state work for a whole volume of this construction.

Schlüsselwörter

  • heating boiler
  • heat transfer
  • economizer
  • fluent
  • solid fuel
Uneingeschränkter Zugang

Analysis of Thermal and Mechanical Stresses of Renault Premium DXi11 460 Eev Four-Stroke Piston

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 169 - 175

Zusammenfassung

Abstract

In this article the engine piston Renault Premium DXi11 430 460 EEV has been analysed using the Finite Element Method. Analysis consider as well heat transfer phenomenon as the thermal and mechanical strains of the piston. Simulations were performed for the point of engine maximum power. Piston material was assumed to be 40HM (1.7225) steel and its properties are delivered basing on available scientific papers. The simulation assumed mean values of heat transfer coefficient, reference temperature and cycle pressure based on engine data, maximum power engine work simulation in AVL Boost software and literature. Part of boundary condition (e.g. cylinder wall temperature) was assumed basing on authors’ engineering intuition and experience. The resulting temperature distribution in the piston was implemented for geometrically nonlinear mechanical FEM analysis. Both the analysis of thermal stresses and stresses of the hot piston in the top dead centre were performed.

Schlüsselwörter

  • Heat transfer
  • temperature distribution
  • four-stroke engine piston
  • Finite Element Method
  • 1D combustion
Uneingeschränkter Zugang

Energetic Balance of Unmanned Ground Vehicle Hybrid Power Transmission

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 177 - 184

Zusammenfassung

Abstract

Article presents the energetic balance of small-unmanned vehicle hybrid power transmission. The vehicle equipped with series hybrid transmission consisted of electric engines connected to the battery pack and small Diesel power generator. In mentioned construction, battery is used as energy buffer and combustion engine is used more as emergency power supply, and is turned on when battery is depleted. In other condition, power generator can be turned off, without reducing power of transmission parameters, except its range. Investigation was divided on two stages. At first stage generator, charging unit and battery were placed outside the vehicle. One piston power generator was feed by Diesel fuel. Fuel consumption of power generator was recorded from AVL fuel balance and energy parameters were recorded by power line analyser of BMR Company. Generator was connected to the direct current power plant. 70 Ah and 48 DC Lithium-polymer battery was charged from the power plant. After charging cycle, small water resistor was used to discharge the battery. Power parameters of discharged battery were measured. This enable to measure balance form tank to the battery. Second stage of the energetic balance determination was to measure internal resistances of vehicle power transmission from current inverter/converter connected to the engine and through the transmission up to the wheels of the vehicle. Power loss of energy at different speed of vehicle wheels without ground contact was measured in respect of power consumption. The series hybrid transmission is consider less efficient than parallel but because of specific configuration of power transmission, it was possible to reach higher efficiency.

Schlüsselwörter

  • balance
  • unmanned vehicle
  • hybrid transmission
  • test stand
Uneingeschränkter Zugang

Experimental Research on Influence of the Fuel Nozzle Geometry on the Fuel Consumption of the Marine 4-Stroke Diesel Engine

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 185 - 190

Zusammenfassung

Abstract

The article presents experimental research that has been carried out on a marine, 4-stroke, 3-cylinder, turbocharged engine. During testing, the engine operated at a constant rotational speed of 750 rpm and a load from 0 kW to 280 kW. The engine was fuelled by diesel oil of known specification and loaded by electric generator with water resistance. The fuel consumption was measured during the engine operation with fuel nozzles with different geometries. The measurement of the fuel consumption was carried out using a weighing system that was designed, constructed, and manufactured by the “KAIZEN” scientific research team at the Faculty of Mechanical Engineering at the Gdynia Maritime University. The results of measurements show changes in the fuel consumption by the engine with the geometry of the injected fuel spray. The research facility is Sulzer’s 3-cylinder, 4-stroke, turbocharged AL25/30 piston engine. The fuel system consists of Bosch injection pumps controlled by a rotation speed regulator. Fuel injectors are centrally located in the cylinder heads of the engine.

Schlüsselwörter

  • marine engine
  • fuel consumption
  • fuel injection
  • experimental measurements
  • compression ignition engine
Uneingeschränkter Zugang

Analysis of Selected Simulated Failure of a Reciprocating Compressor Using Computer Diagnostic System

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 191 - 198

Zusammenfassung

Abstract

In the article, the problems of selected failures that may occur during operation of positive displacement compressors and possible reasons for their occurrence were described. It also included methods for checking performance and diagnostics, with particular emphasis on research using an electronic indicator. Possible mechanical damages of air compressors for various applications have also been characterized. Non-destructive diagnostic methods were described to detect and diagnose damage, taking into account their suitability and limitations in their application. In the further part of the article selected tests results of air compressor, specially adapted to simulation of failures were presented. The test stand has been equipped with sensors for measuring the pressure and temperature of the compressed gas and the sensor of the angular position of the compressor shaft, allowing examining the impact of damage on compressor working parameters. The result of the research was to compare the compressor indicator diagrams in the operational condition, with the simulated failure, and between different failures and to learn the changes of processes taking place inside the cylinder during the compressor’s work cycle. All the test results could be observed in real time, besides the diagnostic software, supporting the tests, made it possible to record measurements. In the described software, it is possible to compare the courses for different cases, to then make a comparative analysis of the results obtained in the state of functional and simulated disability.

Schlüsselwörter

  • piston compressor
  • test stand
  • diagnostic system
  • simulated malfunctions
Uneingeschränkter Zugang

The Usage of a Thermoclimatic Chamber for Technoclimatic Tests of Special Vehicles and Mobile Machines

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 199 - 206

Zusammenfassung

Abstract

Constantly increasing technical and operational demands are set for modern manned and unmanned special vehicles, all − terrain vehicles, and mobile machines. Their producers must comply with very restrictive standards, strict legal regulations, and high customer requirements. They concern not only functionality and efficiency of described objects, but also resistance to the impact of environmental and climatic exposure. Vehicles and mobile machines must be adapted to work in different climatic conditions such as low and high temperature, variable humidity, wind, dustiness, rainfall, variable atmospheric pressure, solar radiation. Verification of the correctness of operation of all these systems installed in machines, vehicles and engineering units requires experimental research in specified and stable climatic conditions. These special conditions can only be implemented in a thermoclimatic chamber. Thanks to these researches, it is possible to confirm the effectiveness of solutions that allow machines to work in extreme climatic conditions, as well as to detect a number of defects and imperfections of the structure, unpredictable at the design stage. The article describes the research procedure certified by Polish Centre for Accreditation and discusses examples of technoclimatic research carried out recently in the thermoclimatic chamber of Laboratory of Technoclimatic Research and Heavy Duty Machines of Cracow University of Technology.

Schlüsselwörter

  • environmental and climatic exposure
  • extreme climatic conditions
  • technoclimatic research
  • thermoclimatic chamber
  • accredited test procedure
Uneingeschränkter Zugang

Stress Distribution in an Anisotropic Beam Subjected to Load

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 207 - 214

Zusammenfassung

Abstract

The article presents the physical equations describing the isotropic and anisotropic materials. Orthotropic material and monotropic are special varieties of anisotropy. Constructional steel, pine wood and polyester-glass composite were tested. The beams were made from these materials. The beams were subjected to external loads. The external load caused internal forces in beams. Calculations of stress distribution were carried out by finite element method (Patran – Nastran software). The calculation results allowed for precise illustrate the distribution of stress especially in layered materials. The load is basically a transmitted through the strong layers of composite. This is illustrated in the figures. Wood is materials of a layered structure and is classified as inhomogeneous materials. Whereas steel is considered as a homogeneous material. Passing from the level of microscopic inhomogeneity to the macroscopic homogeneous level is called homogenization. This method formulates the macroscopic description by homogenizing microscopic properties. For the purpose of mathematical description of a material, the real centre can be substituted by a homogeneous centre. The homogenization method is commonly used to describe the properties of rocks, wood, composites, reinforced concrete, as well as human osseous tissues. The description of the mechanical properties of isotropic materials is based on the theory of elasticity, while the anisotropic materials are based on the anisotropic theory of elasticity. Calculations of anisotropic materials are quite complicated (large number of physical quantities) and sometimes-approximate results are obtained.

Schlüsselwörter

  • isotropic material
  • anisotropic material
  • beam deflection
  • stress distribution in the beam
Uneingeschränkter Zugang

Finishing Treatment of Marine Pump Shafts Made of X5CrNi18-10 Steel

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 215 - 222

Zusammenfassung

Abstract

One of the greatest problems of modern production techniques is the achievement of an appropriate quality at minimal costs and accompanied by the production efficiency increase. Therefore, while designing the production process, the technology used should have a considerable influence on the durability and reliability of machine parts to be produced. During finish treatment, the final dimensions as well as functional properties are imparted to a given element by application of proper treatment type. The engineer has a range of production techniques to choose for the proper surface layer formation. It is crucial to find a suitable solution which will meet the requirements as well as the work conditions of a given machine part. The article presents the results of influence of cutting parameters change on temperature and cutting forces during turning process of stainless steel. A shaft made of 304L stainless steel was used for the research. The cutting process was carried out on a universal CDS 6250 BX-1000 centre lathe. Measurement of cutting forces during lathing process used DKM 2010 turning dynamometer. The turning process was conducted by a cutting tool with CCET09T302R-MF insert by DIJET. During the turning, the following machining parameters were used: cutting speed Vc = 152, 219, 304 m/min, feed f = 0.044, 0.062, 0.083 mm/rev and cutting depth ap = 0.4, 0.8, 1.2, 1.6 mm. The view of the nose radius of cutting tool before and after the turning process was made by the Smartzoom 5 microscope.

Schlüsselwörter

  • turning dynamometer
  • temperature and cutting forces
  • stainless steel
Uneingeschränkter Zugang

A Stochastic Model of Changes in the Operational States of Means of Transport

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 223 - 230

Zusammenfassung

Abstract

In the article, application of a Markov process for modelling the process of transport means operational state changes whose duration times can be estimated by Erlang distribution is presented. The research object is a system of city bus transport operation, used in a selected agglomeration. A homogenous Markov process was assumed a mathematical model of the process of transport means operation. Transformation of a stochastic process, for which distributions of random variables denoting duration times of the states are Erlang distributions, into a stochastic process characterized by exponential distribution of the state duration times, was performed at the costs of the state space extension. The use of a homogeneous Markov process for mathematical modelling of the operation process was dictated by the fact that the process reflects adequately, from the point of view of the research goal, the real operation process. In order to illustrate the process, a hypothetical, simplified calculation example was provided. Reliability of technical objects needs to be maintained at appropriate level, which is the responsibility of the repair and maintenance subsystem ensuring. This subsystem consists of two subsystems. The main tasks of the mobile emergency teams include providing vehicles, that is, buses that are outside the depot with the serviceability state as quickly as possible or hauling damaged buses to technical service stations.

Schlüsselwörter

  • homogeneous Markov process
  • operation process
  • operational state
  • transport means
Uneingeschränkter Zugang

Thermal Barrier Concepts Against Continuous Laser Irradiation

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 231 - 238

Zusammenfassung

Abstract

Rapid development in the high-power laser technology poses new requirements on the thermal protective materials. Military laser applications have been characterized and the examples have been presented. Existing materials, which may be used as a protection against high-energy laser beam, have been discussed. Several concepts of the new thermal barrier materials have been proposed. The proposals include multilayer structures, porous materials, systems with phase change materials (PCMs), and systems with various thermal contact resistance for different contact pairs. Comparative study based on numerical simulation results has been performed to assess efficiency of each proposal.

Three major candidate technologies were considered: the CO2 laser, the HF/DF chemical laser, and the Nd-glass solid-state laser. The CO2 combustion driven gas laser was built in mid-seventies. Its power was 500 kW with the poor beam quality. In the context of thermal protection against laser, high conductive material component in a complex structure might be especially useful, since irradiated surface is usually limited to a small size.

Schlüsselwörter

  • laser weapons
  • thermal barriers
  • multilayer structures
  • phase-change process
  • thermal contact resistance
Uneingeschränkter Zugang

Analysis of Selected Operating Parameters of Engine Powered by a Mixture of Biocomponents and Diesel Oil

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 239 - 244

Zusammenfassung

Abstract

Reaching of high parameters of a drive unit and low pollution of the natural environment is considered to be the most desired effect of motorization. The use of the additive in the form of fatty acid methyl esters to the diesel oil, assumes lowering of harmful fuel gases’ emission and reaching high operating parameters of an engine, such as power and turning moment. Studies on the power output and the turning moment of an engine with self-ignition are presented in the study. The subject matter of the studies was a combustion engine with self-ignition of the power of 80 kW with the direct common rail system and turbo-compressor’s supercharging and with electromagnetic injectors. The tested engine was powered with diesel oil and the mixture of fatty acid methyl esters and the diesel fuel, in proportions 10%, 30% and 50% with an improver, at the standard settings of the fuel injection controllers. The vehicle used for the testing purposes, has been singled out with respect to the specific features, such as: universality of its use as a means of transportation and the opportunity of modification of the injection parameters, resistance to possible unfavourable consequences resulting from the use of the fuel mixture. The studies were conducted on a chassis test house, at full engine’s loading. The vehicle placed on the test house’s rollers, was strapped with belts to the foundation, and then accelerated up to the specific speed and subjected to loading standing in place. In such a manner, the road conditions were simulated. The obtained results of the tests were subject to the statistical analysis. From their analysis it results, that application of the mixture lowers the engine’s parameters to a degree unnoticeable at the time of its operation.

Schlüsselwörter

  • transport
  • means of transport
  • diesel oil
  • biocomponent
  • alternative fuels
Uneingeschränkter Zugang

Motor Vehicle Diagnostics in Military Units

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 245 - 252

Zusammenfassung

Abstract

Transport pertains to all functional areas of the State’s activities on every administrative level. Road transport is a very important branch of global economy and constitutes a part of the logistics network. It pertains to the transportation of cargo, items, and people. Cooperation between the branches of civilian transportation and military logistics must be the focus of continuous improvement efforts. Enhancements in this respect can serve to avoid possible failures and disruptions. The quality and availability of infrastructure plays a significant role, not only with respect to civilian, but also military assets. The condition of the vehicle is important for the safety of road transport. The provision of transport services in a military unit should mainly rely on military-civilian cooperation and effective communications. The condition of the means of transportation has been indicated as a factor influencing transport safety. Employing new technology and solutions enables constant improvements to the diagnostic system, broadening the knowledge and enhancing the skills of the motor vehicle driver in terms of proficiency in operating and maintaining the vehicle used.

Schlüsselwörter

  • motor vehicle diagnostics
  • vehicle operation
  • vehicle condition
  • military-civilian cooperation
  • transportation support
Uneingeschränkter Zugang

Comparative Analysis of the Calculation Methods of the Marine Propeller’s Blade Thickness

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 253 - 260

Zusammenfassung

Abstract

Strength of the propellers with the skewback greater than 25º has to be numerically analysed according to marine classification societies. The finite element method (FEM) is advised for that kind of calculations. Classical and typical propellers (skewback < 25º) may be designed on the base of empirical equations given by the societies. The minimal thickness of the propeller blade is determined by the equations. Each classification society has their own empirical formula. Sometimes, well-designed propeller for one society has not enough strength according to the other society. What is more, propellers designed according to the empirical formulas might be not optimal. Comparative analysis of the marine propeller’s blade strength has been described in the article. Calculations of the propeller’s blade thickness have been done by two international classification societies’ empirical formulas (ABS and DNV). The results have been compared with Finite Element Method calculations (NASTRAN program). The methodology of propeller static strength vibration analyses is presented. Numerical calculation methodology is based on solid-state mechanics with loadings determined by fluid mechanics calculations. Steady state and transient fluid flow of the propeller’s working conditions were taken into account. In order to determine the optimal modelling method of the propeller several different numerical models were compared, including free model of whole propeller and single blade with boundary conditions placed in the foot. The propeller optimization was the main target of the analyses. Propeller blade thickness might be reduced after FEM method analysis - the propeller mass saving can be achieved.

Schlüsselwörter

  • marine propeller
  • strength
  • vibration
  • solid structure in fluid
  • FEM modelling methodology
Uneingeschränkter Zugang

Spectrofluorimetry of Chosen Distillates of Oil after Pyrolysis of Scrap Tires

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 261 - 268

Zusammenfassung

Abstract

One of way to obtain liquid hydrocarbons can be pyrolysis of scrap tires. The hydrocarbon substances produced by this method may be an addition to traditional fuels, i.e. gasolines or fuels for diesel engines. In laboratory conditions at Department of Mechatronics of University of Warmia and Mazury there were obtained pyrolytic products and prepared three distillates related to temperatures 160, 204 and 350ºC. Analyses of shapes of fluorescence spectra were carried out in Department of Physics of Gdynia Maritime University. Spectra of fluorescence were prepared applying the spectrofluorimeter Hitachi F-7000 FL, which allows applying of excitation wavelength from 200 nm until 600 nm, whereas analysing of emitted, can be performed until 750 nm. In here reported study excitation and emission range for the most intense fluorescence are presented. There were prepared four solutions of pyrolytic products in the n-hexane: 4 ppm, 20 ppm, 100 ppm and 500 ppm. In order to show dependence of intensity fluorescence and shapes of excitation-emission spectra on type of distillate and concentration both kind of visualization – three-dimensional and as contour maps – are shown in this article. In analysed range of wavelengths, intensity of fluorescence grows with concentration of oil, whereas structure of the shape of spectra simplify when concentration increases. The presented effects associated with the fluorescence of pyrolysis products allow to predict the possibility of developing a method for determining the content of these substances in mixtures with petroleum refining products and other liquid hydrocarbons.

Schlüsselwörter

  • fuels
  • used car tires
  • pyrolysis
  • fluorescence
  • excitation-emission spectra
Uneingeschränkter Zugang

Properties of a Three Disc Cycloid Gear as a Result of Bench Test

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 269 - 280

Zusammenfassung

Abstract

The most common design solution are cycloidal gearboxes with two discs, in which the reaction forces of bearings from the working discs create a bending moment on the high-speed input shaft, additionally affecting bearings. In the article are presented the results of tests of the cycloid gear prototype with three discs. Instead of the second disc, the introduction of two side discs, 1800 from the centre disc, allows you to reduce this moment to zero. To compensate for the unbalance of the shaft, the side discs have half the width of the centre disc. Each disc works with its own, separate set of bronze rollers, separated by Teflon washers, which should reduce the friction forces. In the article are presented the results of the tests of the cycloid gear prototype determining basic parameters such as efficiency, torque fluctuations on the input and output shaft, housing vibrations in three directions. FFT analysis of registered parameters showed high compliance of the designated frequencies for different measured signals. The assumed advantages, i.e. high efficiency and low vibration level in the tested range, were confirmed. The results are presented in the form of three-dimensional graphs as functions of speed and torque. High efficiency (80-90) % was obtained for load moments above 150 Nm, which is practically independent of the rotational speed with which the cycloid gearing works. The oil temperature during the tests was maintained in the range of 36°C ± 2°C. The maximal torque of the cycloidal gear was 500 Nm.

Schlüsselwörter

  • cycloidal gear
  • efficiency
  • vibrations
Uneingeschränkter Zugang

E-REV’s Hybrid Vehicle Range Modeling

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 281 - 286

Zusammenfassung

Abstract

Article presents the influence of battery capacity and electric generator power on a series hybrid vehicle range. Vehicles equipped with increased battery capacity and small power generator are special type of series hybrid vehicles called Extended Range Electric Vehicles – E-REV. The increasing number of hybrid and electric vehicles increases the demand for durable and efficient sources of energy storage for vehicles.

The hybrid vehicle’s battery driven range is increased as battery power density is increased and its cost is decreased. This is due to the battery cell cost decreasing and improvement of cell chemistry. That cause higher and higher distance driven on electric mode in hybrid vehicles. First series hybrid vehicle engine power was equal to engine powered the vehicle’s wheels. Nowadays, series hybrid vehicles are more electric vehicles with small power generator (piston or turbine engine. In such a constructions, battery is used as an energy buffer and combustion engine is used more as emergency power supply.

To minimize this phenomenon, manufacturers use counteracting solutions that include mounting additional cells in the battery that are switched on when the battery controller identifies a particular battery cell’s failure or high degradation. This is due to the deep and shallow discharges of the battery, the numbers of charging and discharging cycles, and the age and technology of battery packs.

AMESim software was used for the simulation of the E-REV hybrid vehicle range. The research was based on modelling the range of the vehicle with different battery capacity works with power generator of different power. By modelling different capacity of battery and power of small generator, it is possible to determine the vehicle range.

Schlüsselwörter

  • battery
  • simulation model
  • electric vehicle
  • E-REV
Uneingeschränkter Zugang

Potential of Biomass-to-Fuel Conversion Technologies for Power and Means of Transport

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 287 - 294

Zusammenfassung

Abstract

Reduction of CO2 emissions in Poland (excluding transport) should be related to a change in the structure of electricity production sources. Similar actions have been taken by many European countries. In 2017, in the European Union’s power industry, the largest emitters were dominated by coal-fired power plants in Germany (seven power plants). However, the leader of this ranking turned out to be the Belchatów power plant owned by the Polish Energy Group (PGE). Renewable energy is energy obtained from natural processes. It should be obtained in a way that would not cause a deficit of natural resources (renewed in a short time) to have a limited impact on the environment. The purpose of promoting and using renewable energy sources (RES) is to reduce the harmful effects of energy on the natural environment, primarily by limiting greenhouse gas emissions (water vapour, CO2, CH4, CFC, N2O, halon, ozone and industrial gases HFC, PFC, SF6). Biomass is the most widely used renewable energy source currently used. The study of the literature and comparison of the set parameters for different types of biomass in the given order shows that Virginia mallow has the highest usefulness for energy purposes. Considering the fact that both cashew and coconut (shells) cannot be grown due to the climate prevailing in Poland, Virginia mallow seems to be the best alternative for traditional fuels used in the energy sector in the analysed group. Virginia mallow has competitive properties to wood biomass and hard coal only significantly supercedes in terms of calorific value. The energy properties of Virginia mallow can additionally be improved as a result of the torrefaction process. In addition, in the literature on the subject, attention is paid to the fact that mallow may be grown on less-favoured soils and the process of its collection – in contrast to other such plants – does not require the use of specialized agricultural machinery.

Schlüsselwörter

  • renewable energy sources
  • biomass
  • sida hermaphrodita
  • torrefaction
  • renewable fuel
Uneingeschränkter Zugang

The Effect of the Addition of Nanotubes Upon the Thermo-Protective Properties of the Aramid-Reinforced Composite

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 295 - 301

Zusammenfassung

Abstract

The aim of this article is to present findings concerning the thermo-protective research into ablative materials. The authors analysed the impact of the addition of carbon nanotubes upon the selected ablation properties, i.e. the ablation mass waste, average linear rate of ablation and the backside temperature of the specimens. The performed tests as well as the obtained findings allowed formulating a number of conclusions, which are useful in creating future composites.

Composition of individual test samples; ablation testing; average relative ablation mass loss, depending on the volume share of carbon nanotubes; average ablation rate, depending on the volume share of carbon nanotubes; temperature of the rear surface of the insulating sample, depending on the volume share of carbon nanotubes; temperature inside the composite, depending on the volume share of carbon nanotubes; comparison of the temperature of ablation surface, temperature inside the composite and temperature on the rear surface of the wall of carbon nanotubes after the exposition to a heat flux are presented in the article.

Schlüsselwörter

  • ablative materials
  • composites
  • thermal resistance
  • ablation properties
Uneingeschränkter Zugang

Evaluating Combustion, Performance and Emission Characteristics of CI Engine Operating on Diesel Fuel Enriched with HHO Gas

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 303 - 311

Zusammenfassung

Abstract

Research of efficient and ecological parameters was carried out with compression ignition (CI) engine using diesel fuel and additionally supplied hydrogen and oxygen (HHO) gas mixture. HHO gas is produced by electrolysis when the water was dissociating. At constant engine’s brake torque and with increasing HHO gas volumetric concentration in taken air up to 0.2%, engine efficient indicators varies marginally, however, with bigger HHO concentration these parameters becomes worse. HHO increases smokiness, but it decreases NOx concentration in exhaust gas. Numerical analysis of combustion process using AVL BOOST software lets to conclude that hydrogen, which is found in HHO gas, ignites faster than diesel fuel and air mixture. Hydrogen combustion before TDC makes a negative work and it changes diesel fuel combustion process – diesel ignition delay phase becomes shorter, kinetic (premixed) combustion phase intensity gets smaller.

Schlüsselwörter

  • CI engine
  • HHO gas
  • engine efficiency
  • emission
Uneingeschränkter Zugang

Diagnostics and Analysis of Jet Engine Malfunctions

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 313 - 318

Zusammenfassung

Abstract

The article describes emergency situations occurring in the propulsion system of an aircraft with the jet engine used in Poland on planes such as MiG-29 or F-16. The article also presents statistics of polish aircrafts damage over the years. Due to the technological progress of turbine engines used in fighter aircraft, the authors decided to discuss the issue of monitoring emergency states in this study. In particular, efforts have been made to ensure that damage to the aircraft engine can be prevented by monitoring its operation with the equipment available on the aircraft. Counteracting phenomena that occur in the jet engine can lead to permanent damage; can lead to an increase in the safety of the pilot and the local population, but also to a reduction of costs. The authors also decided to se the threats that occur during take-off and landing, and the flight when they land outside the plane. Jet engines are almost reliable and most common cause of engine damages as the analysis shows are foreign bodies, particularly dangerous for a turbine engine on or near the runway, as well as birds, which provides to mechanical damage of engine. Securing the airport against foreign objects on the runway is one of the most important tasks of ground staff.

Schlüsselwörter

  • jet engine
  • aircraft
  • diagnostics
  • safety
Uneingeschränkter Zugang

Use and Calibration of 5-Hole Pressure Probes to Measurement of Airflow Velocity

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 319 - 327

Zusammenfassung

Abstract

Multi-hole probes are simple and robust device to measurement of flow velocity magnitude and direction in wide range of angles of attack – up to 75°. They become popular as they may be easily use to measurement of unknown flow velocity, while optical methods, like PIV or LDA, require some knowledge about the flow for proper setting of measurement devices. Multi-hole probes are also more lasting in comparison with CTA hot-wire probes, which may be damaged by a dust.

A multi-hole probe measures air pressure with one pressure tap on its tip and a few (usually 2, 4, 6 or more) taps on conical or semispherical surface of the probe tip. Based on measured pressures, some non-dimensional pressure coefficients are calculated, which are related to flow velocity direction (i.e. two angles in Cartesian or spherical coordinate system) and magnitude. Finding relations between these parameters is relatively complex, which for years was limiting application of multi-hole probes.

The article summarizes methods of multi-hole probes calibration and use, which may be classified as nulling and non-nulling methods or – with other criteria – as global and local methods. The probe, which was presented in the article, was the 5-hole straight probe manufactured by Vectoflow GmbH and calibrated in the stand designed and manufactured at the Institute of Aviation. The local interpolation algorithm has been used for calibration, with some modifications aimed on mitigate of mounting uncertainty, which is related with the non-alignment of flow velocity direction and probe axis

Results of calibration showed that the accuracy of presented methodology is satisfactory. The standard measurement uncertainty was assessed for 0.2° for the pitch angle and yaw angle, which is better than accuracy declared by the probe’s manufacturer (1.0°). The measurement uncertainty of the flow velocity is approximately 0.12 m/s, similarly like in manufacturer’s data.

Schlüsselwörter

  • aerodynamic measurement
  • turbomachinery
  • measuring devices
  • flow direction measurement
  • multi-hole probes
Uneingeschränkter Zugang

Adaptive Landing Gear Control System Assumptions

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 329 - 333

Zusammenfassung

Abstract

In the present time, landing energy dissipation process in aviation shock absorber design is optimized for the most demanding, but still safe, landing scenario (reserve energy landing conditions). Most of the current solutions are based on a fixed hole (orifice) or a set of holes regulating hydraulic fluid flow in the shock absorber. This approach although safe provides no optimization of the forces acting on the fuselage in different (less energetic than limit energy) conditions. Due to the progress in hydraulic flow control, it is possible to design and control a proper system for extended optimization of the landing process energy dissipation. The complete system contains two parts, one of which is a direct flow executive electro-mechanical system and second of which is an electronic control system. The electronic control system directly manages executive system via a set of inputs, thus creating proper output signals for the optimal flow control.

In this article, the author presents the idea of the computer control part of the adaptive hydraulic flow control system. The author describes a set of possible control input and output signals both external and internal, from the landing gear reference system, characterizing their role in the landing process. The author also defines possible control algorithms selected to fit the assumptions of the adaptive landing gear system. Finally, the author presents a proposal for the laboratory grade control system for future testing of the assumptions described in this article.

Schlüsselwörter

  • laboratory testing
  • landing gear
  • adaptive control
  • control system
Uneingeschränkter Zugang

Strain Gauge Pin Based Force Measurement

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 335 - 340

Zusammenfassung

Abstract

In this article authors present force measurement method based on strain gauge measuring system installed inside pin, which is a part of light helicopter Main Landing Gear Shock Absorber. Strain gauges in full bridge configuration were installed inside the mounting pin (upper one – fuselage side). Placement and type of strain gauges were selected during the preliminary tests, which verified the validity and conditions of the force measurement. Preliminary tests allowed verification and selection of an optimal measurement system by testing two types of them. The impact on force according to the angle of force vector direction was also verified. Preliminary tests of the strain gauges equipped pin were performed using quasistatic tests stand – 40 T hydraulic press for applying force acting on shock absorber and pin. Whole measuring system is planned to be used in real time analysis of shock absorber force acting on fuselage mounting node.

The strain gauges allows measurement of force in any place of the structure, the article presents the advantages of the system located inside pin. Additionally, the installation technologies of strain gauges in hard-to-reach places are presented. The article is summed up with an analysis of the problems, which arise during the installation and measurement process using strain gauges installed in such a specific place.

Schlüsselwörter

  • strain gauges
  • landing gear
  • test stand
  • measuring system
Uneingeschränkter Zugang

Performance Requirements and Simulation of Rotor Operation for High-Mountain Rescue Helicopter

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 341 - 348

Zusammenfassung

Abstract

Simulation results concerning performance of helicopter suitable for high-mountain rescue operations are presented. Including operations in regions of the highest Himalaya Mountains, the possibility of hover ceiling out of ground effect (OGE) at 10,000 m above sea level is assumed. Demand of high ratio of developed lift to power required for hover leads to choice the coaxial rotor configuration as the best for rescue helicopter, which can operate in extremely high mountain environment, and gives good stability features in wind gust conditions in comparison with single main rotor helicopter. For performance calculations the simple model of helicopter is applied, which consists of fuselage point mass and rotor disk. The cases of partial and total power loss are considered to define range of H-V zones and possibilities of flight continuation due to height of landing surface over level of sea. The rotor blades and rotor loads are calculated applying detail model of elastic blade, which includes effects of its deflections due to out-of-plane bending, in plane bending, and torsion. The Runge-Kutta method is applied to solve equations of motion of rotor blades with taken into account effects of blade pitch control and variable deflections of blades. According to Galerkin method, the blade parameters of motion are treated as a combination of torsion and bending eigen modes of the rotor blades. Elastic blade model allows defining behaviour rotor blades in selected states of flight: hover, level flight, wind gust conditions, and pull-up manoeuvre. The results of simulation for upper and lower rotor for blade deflections and loads are shown in form of time-run plots and rotor disk distributions. The simulation investigation may be applied to define features of helicopter configuration suitable for operation in extremely high mountain conditions.

Schlüsselwörter

  • rescue helicopter
  • high-mountain operations
  • rotor blade deformation
Uneingeschränkter Zugang

The Effect of Using the Kline-Fogleman Modification Upon the Coefficient Characteristics of Aerodynamic Forces in the Airfoil

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 349 - 356

Zusammenfassung

Abstract

The wing is the main aircraft construction element, whose main task is to produce the lift, balancing the aircraft weight as well as ensuring the execution of all flight states for which the aircraft was designed. The selection of appropriate airfoils or the development of new ones is one of the most important constructions goals. As a rule, constructors aim at ensuring a sufficiently large lift with little aerodynamic drag in order to increase the scope of utility angles of attack and such shaping of these characteristics so that the aircraft performance, close to the critical angles of attack, guarantees an adequate level of safety. One of the methods of improving the aerodynamic properties of airfoils is the Kline-Fogleman modification. It involves an application of a step into the airfoil contour at a place. It enforces the creation of a swirling air stream, preventing the separation and maintaining airflow over the profile and thus the reduction of drags, as well as delaying separation. The use of this type of a solution is justified when designing unmanned aerial vehicles, of small sizes, which move with slow speeds and sometimes-large angles of attack, including those close to critical angels of attack. The Kline-Fogleman modification decreases the likelihood of aircraft stalling.

The aim of this work is to present an analysis of airflow over NACA0012 airfoil with Kline-Fogleman modification. The calculations were made by solving the problem of numerical fluid mechanics. For calculations, the Comsol Maribor programme was used. The investigation focused on several different airfoil modifications (KFm-1, KFm-2, KFm-3). This enabled a selection of a solution, providing the most desirable aerodynamic characteristics.

Schlüsselwörter

  • airfoil
  • CFD
  • aerodynamics characteristics
  • Kline-Fogleman modification
  • NACA0012 airfoil
Uneingeschränkter Zugang

Time – Frequency Dynamic Characteristics 2D in the Quality Assessment of Welded Joints

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 357 - 361

Zusammenfassung

Abstract

The authors of the article have been looking for a new parameters and dynamic characteristics, which can be applied to non-destructive testing of welded joints. All characteristics have been based on recorded data generated during the vibration tests of welded joints with and without failures. The article deals with the methods of assessing welding joints using 2D: time – frequency dynamic characteristics. A calculation procedure used for analysing simultaneous changes of the response modules, registered by acceleration sensors was presented. Vibrations amplitudes were transformed to a function of time and frequency (simultaneously) and presented over 2D time – frequency characteristics. The analyses of the characteristics were performed for a plate without any welded joint, for a plate with non-defected welded joint and for a plate with a welded joint defected by an edge bonding. Having analysed registered 2D time – frequency dynamic characteristics it can be noticed that presenting the responses analysed simultaneously over the time and frequency allows evaluating if examined system maintains non-linearity and, at the same time, it allows to indirectly assess the quality of the welded joint. The proposed measure parameters of the quality of a welded joint can be defined as a dispersion of colours on the obtained characteristics. The faults (and the vibration nonlinearity) of the welded joints is bigger if the dispersion is greater.

Schlüsselwörter

  • welding
  • welded joints
  • non-destructive testing
  • NDT
  • SHM
  • vibrations
  • time – frequency characteristics
Uneingeschränkter Zugang

Comparison of the Environmental Impacts of a Plug-in Hybrid and a Full Electric Car Using Life Cycle Assessment

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 363 - 369

Zusammenfassung

Abstract

Full electric (FEV) and plug-in hybrid (PHEV) vehicles are promising, forward-looking technologies to reduce greenhouse gas (GHG) emissions and other pollution related to road transport. The powertrain of a FEV is composed of a battery, control electronics and the electric motors. A PHEV has much lower battery capacity but it contains an extra internal combustion engine and gearbox. Many argue that FEVs are more energy-efficient than internal combustion engines. However, this energy needs to be stored in heavy, large-capacity battery packs that require plenty of energy and resources to produce as well as highly polluting rare earth elements mining. In this article, an environmental comparison of FEVs and PHEVs is shown using life cycle assessment (LCA). To make the comparison realistic, two models similar in size and power have been selected: Volkswagen E-Golf FEV and Volkswagen GTE PHEV.

Results show that the production of FEVs need more energy and it means more burden on the environment however during the use phase it causes less emissions. Since the local electricity production mix and, in case of PHEVs, the user behaviour highly affects the results, three different countries (Hungary, Poland and Norway) and two different use types are considered. The quantified environmental footprints as well as the break-even distances are presented. Sensitivity of the results towards the assumed conditions during the whole design lifetime of the vehicles is discussed.

Schlüsselwörter

  • full electric vehicle
  • plug-in hybrid electric vehicle
  • life-cycle assessment
Uneingeschränkter Zugang

Analysis of the Use of OBD II / EOBD Congestion Diagnostics in the Light of Vehicles Operation and their Technical Condition

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 371 - 378

Zusammenfassung

Abstract

Transport in human life has played a key role since ancient times. At the turn of years it has evolved, initially using only the power of human legs, then the animals until use internal combustion engines. The first internal combustion engine was presented by Brackenburow in 1836. The construction showed a very desirable type of combustion engine – burning a mixture of hydrogen and oxygen and expelling clean water as exhaust gas. However, the invention was abandoned due to its innovativeness and lack of trust in it. The topic was again taken in 1860 presenting a two-stroke engine using a mixture of natural gas and air with spark ignition. Striving for even greater perfection, Rudolf Diesel in 1893 presented and patented the first self-ignition diesel engine. The first solution, although used today, has shown that automotive engines leave a significant margin of reliability.

The operational reliability of internal combustion engines is important in relation to the conditions of their operation and technical condition. The impact of toxic substances in exhaust gases and their impact on the natural environment these days is an important issue.

One of the forms of work on the problem is the current diagnosis of engine operation. This was possible thanks to the use of the OBD I system, which was later transformed into OBD II / EOBD and the result of the test results obtained to the applicable EURO standards. The system allows testing during a road test in normal car operation. Using the OBD recorder, the operation of an example vehicle will be analysed in various operating conditions, and the obtained results will provide diagnostic possibilities.

Schlüsselwörter

  • on-board diagnostics
  • diagnostic procedures
  • OBD
  • OBD II
  • EOBD
  • reliability of engines
  • operation of engines
Uneingeschränkter Zugang

Multidimensional Simulation of Combustion and Knock Onset in Gas Engines

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 379 - 389

Zusammenfassung

Abstract

Natural gas fuelled internal combustion engines enable efficient energy conversion with relatively low environmental impact. Depending on the specific application, the available fuel quality, and the emission regulations to be fulfilled, different types of gas-engine combustion systems are in use. The major performance and hence efficiency limiting factors in gas fuelled engines are related to the lower ignitability of natural gas at part load and the appearance of abnormal combustion (knock) at high load conditions. This article provides an overview of the multidimensional CFD simulation workflow for the investigation and assessment of flame propagation and knock onset characteristics in different types of natural gas fuelled internal combustion engines. The most common approaches for simulating flame propagation/combustion under engine conditions are presented together with selected models for describing the pre-flame reactions finally leading to knock onset in the unburned in-cylinder charge ahead of the flame. Based on selected application examples, the models’ performance and capabilities with respect to reflecting the essential characteristics of flame propagation and knock onset are presented.

Schlüsselwörter

  • gas engines
  • simulation
  • combustion
  • efficiency
  • knock onset
Uneingeschränkter Zugang

Combustion of Mixture of Diesel Fuel with Gasoline in a Compression Ignition Engine

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 391 - 398

Zusammenfassung

Abstract

Paper presents results of experimental investigation of combustion process of diesel-gasoline blend in compression ignition direct injection engine. The researches were conducted for constant load of engine at constant rotational speed. Operating parameters of engine powered with diesel-gasoline blend were at the same level as for engine powered by pure diesel fuel. The preliminary study was conducted using CFD modelling. Based on encouraging modelling results preliminary experimental research was carried out. It turned out that it is possible to co-burning diesel with the gasoline as a blend. A mixture of 20, 40 and 60% of gasoline with diesel was used. It was concluded that an increase in gasoline fraction in blend causes delay of start of the combustion process. The homogeneity of the fuel-air mixture was improved due to longer ignition delay, which is accompanied by higher values of pressure rise rate. With 20 and 40% of gasoline fraction causes higher peak pressure compared to reference fuel-burning ware obtained. Up to 40% of gasoline fraction, the BSFC was kept at the same level as for reference fuel. It was observed that with the increase in gasoline fraction up to 40% NOx emission increased as well. Based on the carried out tests it can be stated that it is possible to co-burn gasoline with diesel in a compression ignition engine while maintaining the invariable engine operating parameters and exhaust emissions.

Schlüsselwörter

  • combustion
  • engine
  • diesel
  • gasoline
  • combustion phases
Uneingeschränkter Zugang

Method for Estimating the Static Friction Degree in the Slide Pair of the Miniaturised Electrohydraulic Servomechanism

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 399 - 407

Zusammenfassung

Abstract

One of the most important parameters specifying the usability of the miniaturised electrohydraulic servomechanism includes a static friction degree in its slide pairs, i.e. resistance of the slider’s movement from rest after some time of its staying at rest under pressure. Therefore, at the stage of designing and construction of the electrohydraulic servomechanism, it is important to determine the greatest static friction degree, which may arise in the slider hydraulic pair of this device during its operation. The objective of this article is to present a method for estimating the maximum static friction values in the slide pair based on the extreme value theory. The operation and loading conditions of the slide pair of the electrohydraulic servomechanism for the unmanned aircraft control system were described. The procedure for estimating the maximum static friction degree in the slide pair with the use of the extreme and probabilistic grid was presented. The extreme and probabilistic grid structure was based on the Gumbel probability graph. The graphic presentation of results of the static friction experimental studies in the slide pair on the extreme and probabilistic grid was discussed. By using the graphics method, the empirical dependence of the static friction force in the slide pair on the working fluid pressure in the hydraulic drive (loading conditions) was determined. A practical example of estimating the maximum values of the static friction force that may occur in the slider hydraulic pair of the miniaturized electrohydraulic servomechanism is shown.

Schlüsselwörter

  • operation
  • hydraulic drive
  • electrohydraulic servomechanism
  • pressure
  • friction force
Uneingeschränkter Zugang

The Influence of the Blades Leading Edge Anti-Erosion Protection on Main Rotor Performances

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 409 - 414

Zusammenfassung

Abstract

This article presents the influence of rotor blade airfoil shape on main rotor performances. In this case, we analysed the influence of anti-erosion tape, which is applied to the leading edge of the blade to protect the blades from environmental conditions. In Gyro-Tech Innovation an Aviation Company and Institute of Aviation the independent tests of helicopter and gyroplane main rotors were performed. Research includes: bench tests, on the test stand for dynamic testing of insulated rotors and tests on two flying constructions, gyroplane Cavalon produced by AutoGyro GmbH Company and ultralight helicopter Dynali H3. On the test bench, a two-blade rotor, used in ultralight and unmanned helicopters, was tested. In article, the authors present importance of the proper selection and application of anti-erosion coatings on rotor blades. Discuss the behaviour of the above-mentioned constructions with main rotor blades leading edge covered anti-erosion tape, during flight tests. The results of bench tests, including the comparison of polar curves of the main rotor with anti-erosion coating and without were also presented and discussed.

In the summary of this article among others the solution of technological pocked introduced in the rotor blade, corresponding to the thickness of the anti-erosion tapes, in such way that after tape is applied it does not change the contour of the blade airfoil were presented.

Schlüsselwörter

  • airfoil
  • rotor blades
  • flight tests
  • light and ultra-light rotorcrafts
Uneingeschränkter Zugang

Detailed Modelling of the Internal Processes of an Injector for Common Rail Systems

Online veröffentlicht: 11 Nov 2019
Seitenbereich: 415 - 426

Zusammenfassung

Abstract

In the last few decades exhaust emissions of road vehicles have decreased dramatically, owing to the more and more stringent emission standards issued by the legislative bodies of different countries, combined with the necessity of cleaner, better performing vehicles from society side. The introduction of Common Rail (CR) injection systems has been a great step towards achieving this target, thanks to its flexibility in fuel injection pressure, timing, and length, along variable engine load conditions. However, it is highly time and resource consuming to set up the injection system for all operating points of different engines, moreover, as the injection is a small scale, high speed process, the behaviour of the internal processes is challenging to measure. The best solution for these problems is to create a detailed model of the injector, where all the hydraulic, mechanic, and electromagnetic subsystems are represented, this way the internal working conditions can be analysed and resources can be saved.

In this work, a detailed model of a first generation CR injector for commercial vehicles is presented and validated against needle lift data. The fluid dynamic and mechanic sub-systems are presented in details to thoroughly investigate the working principles of the injector internal parts. The fluid dynamic subsystem contains the chambers, holes, and throttles of the injector, while the mechanic subsystem models the motion and behaviour of the internal parts. The main features of the injector internal working conditions are described and analysed. Apart from the needle lift, these included solenoid anchor, pin and control piston lifts, the control chamber pressure and the mechanical force acting on the anchor. Five test cases were chosen on a medium duty test engine to represent a wide range of operation points from full load to idle and the simulated results were compared to the measured data. The simulated control piston movement accurately matched the measured curves in every test case.

Schlüsselwörter

  • Common Rail
  • injector
  • simulation
  • modelling
  • internal combustion engines

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