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 26 (2019): Heft 2 (June 2019)

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

Suche

25 Artikel
Open Access

Influence of the Cyclic Hardening Model on the Results of the Numerical Analysis of Fatigue Life on Example of the Compressor Blade

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 7 - 14

Zusammenfassung

Abstract

The main goal of the presented work is to determine the impact of the cyclic hardening model on the numerical results of the ε-N fatigue test. As an object of study, compressor blade (from PZL-10W helicopter engine) was used. The examined blade was made of EI-961 alloy. In numerical analysis, a geometrical model of the blade with a preliminary defect was created. Geometrical defect – V-notch was created on the leading edge. This defect was introduced in order to weaken the structure of the element and the possibility of observing the crack initiation process (in experimental tests). Material data to ε-N analysis, based on Manson-Coffin-Basquin equation, were estimated for Mitchell’s model. This model was built based on strength data provided by the steel producer. Based on three different models of cyclic hardening (Manson, Fatemi, and Xianxin), a number of load cycles were calculated. Load cycle during numerical analysis was represented as resonance bending with an amplitude of displacement equal to A = 1.8 mm. Obtained results were compared with experimental data. Additionally, the analytical model of ε-N fatigue (depending on the cyclic hardening) was prepared. All the work carried out has been summarized by a comprehensive comparative analysis of the results. Obtained results and dependencies can be used in the selection of an appropriate model of cyclic hardening in further fatigue tests of many aerospace elements.

Schlüsselwörter

  • fatigue life
  • compressor blade
  • aircraft engine
  • cyclic hardening
  • numerical analysis
Open Access

Properties of AlMg3 Aluminium Alloy Joints Welded by Electron Beam Melting

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 15 - 20

Zusammenfassung

Abstract

Electron beam welding, called electron welding consists in penetrating the elements being welded with heat obtained from the elements’ bombardment in vacuum with concentrated electron beam of high energy. Concentration of the electron beam of high kinetic energy in a very small space results in generating the heat of high concentration causing melting of material in high depth. During the metal melting the electron beam makes a narrow weld of little heat affected zone (HAZ). This paper presents the test results on selection of parameters of electron beam welding of 12 mm thickness sheets of AlMg3 aluminum alloy. The beam electron melting through was carried out in vacuum by means of the welding machine WS-15 KW/100 KV. Before melting, the sheets were degreased in tetrachloroethylene and oxides were removed with 15% solution Na2Co3. The influence of electron beam melting through of sheets on their mechanical properties was tested as well as resistance to stress corrosion cracking and resistance to corrosion in fast seawater flow (10 m/s). The slow strain rate stress corrosion tests in the air and artificial seawater were performed. It was found that electron beam melting through of the AlMg3 alloy does not decrease the mechanical properties in comparison to the native material. The crack during the static tension test had ductile character and proceeded in the native material. AlMg3 alloy melting with electron beam shows a very good stress corrosion resistance.

Schlüsselwörter

  • electron beam welding
  • aluminium alloy
  • stress corrosion
Open Access

The Possibility of Applying Acoustic Emission Method for Monitoring Lathing Process

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 21 - 27

Zusammenfassung

Abstract

Nowadays acoustic emission (AE) method is used in many fields of science, including in the diagnosis and monitoring of machining processes such as turning, grinding, milling, etc. Monitoring of turning process allows ensuring stable conditions of treatment. Stable conditions of turning process have a great impact on the quality of the surface. This is especially important during finishing treatment.

The research was carried out on a universal ZMM-SLIVEN CU500MRD lathe centre-using tool with removable insert SANDVIK Coromant WNMG 080408 – WMX Wiper. Lathing process was performed on the shaft of 74 mm in diameter made of S235 steel.

The research was carried out at constant cutting speed v = 230 m/min. Changed parameters were feed f = 0.1; 0.2; 0.4 mm/rev and cutting depth ap = 0.5; 0.75; 1 mm. In the research was used a set of acoustic emission Vallen System. The kit includes: 4 channel signal recorder AMSY 6, two measurement modules ASIP-2/S, preamplifier with a frequency range 20 kHz – 1 MHz and the strengthening of 34dB and AE signal measurement sensor type VS 150M, with a frequency range 100 – 450 kHz. During the study, the acoustic emission (AE) generated during the lathing process were recorded parameters e.g. amplitude, number of events – hits, the effective value of the signal (RMS).

The test results indicate, that the higher instability of the process was during turning with parameters: ap = 0.75 mm and f = 0.1 mm/rev. The study can be the basis for the use of acoustic emission method for monitoring lathing process to ensure stable conditions of that process and the same to obtain a high quality surface.

Schlüsselwörter

  • Acoustic Emission (AE)
  • diagnostic
  • finishing treatment
  • lathing
  • cutting parameters
Open Access

The Effect of Parameters and Geometry Cutting Edge After Turning of the Duplex Cast Steel on the Maximum Tool Flank Wear

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 29 - 35

Zusammenfassung

Abstract

It is important to shape the required properties of the surface layer in the technological process. This issue is an important problem due to the ability of the kinematic pair elements to the required reliable operation of machine parts. The latest generation devices work with increasing operational loads. This forces the search forever-newer construction materials or innovative manufacturing engineering technologies that would ensure high reliability and durability of machine components. For mechanical engineering, continue to be used on steel structures of machine parts. In the petrochemical and shipbuilding industry, stainless steels are very poplars. Those materials are used in the constructions of seawater and acid installations. Currently, a newer material with more favourable properties is two-phase stainless steel. This is the so-called duplex steel. It can be applied to pump shafts in acid or seawater solutions. Duplex cast steel is a difficult-to-cut material. It is important to determine the effect of cutting parameters on the surface quality of the shafts and wear of cutting edge. Traditional methods of finishing surface treatment of shafts are machining (turning, grinding, superfinishing). Considering the possibilities of equipping a marine power plant workshop, it would be best to use machining by turning.

The paper specifies the relationship between the wear of the cutting edge and the geometrical structure of the machined surface as well as the type of tool material used and the shape of the cutting inserts.

Schlüsselwörter

  • turning
  • surface roughness
  • duplex cast steel
  • cutting edge
  • flank wear
Open Access

Impact of Processing Parameters on Surface Roughness and Strain Hardening of Two-Phase Stainless Steel

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 37 - 44

Zusammenfassung

Abstract

Products used in the construction of machines and shipbuilding as well as petrochemical industry, such as shafts, bars, pipes and the like from two-phase stainless steel are currently very popular. It is required that they meet certain quality criteria. They must be characterized by suitable properties of the surface layer to meet the requirements of potential buyers.

In the article impact of processing parameters on the degree of relative strain hardening and index of surface roughness reduction were presented. The burnishing process was carried out for two-phase stainless steel. Burnishing process of the shafts neck was performed using burnisher roller. The experimental research were obtained in the surface layer increase in hardness and the material ratio curve a convex shaped, which, taking into account the load capacity of the surface will be directly affected by its resistance to wear and corrosion. The experimental research by application of the burnishing process was made in the Laboratory of Production Engineering. After the studies it was found that the hardness of the surface layer and the roughness of the shaft necks an important influenced by technological parameters of processing (burnishing speed, feed rate and depth of burnishing). The objective of applying burnishing process may be, for example, the need to increase surface smoothness and dimensional accuracy of part.

Schlüsselwörter

  • burnishing process
  • index of surface roughness reduction
  • degree of relative strain hardening
  • two-phase stainless steel
Open Access

Analysis of the Possibility of Using Low Speed Two-Stroke Dual-Fuel Engines for Propulsion of Sea-Going Vessels

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 45 - 52

Zusammenfassung

Abstract

The use of gas/LNG to supply marine engines in addition to tangible economic benefits is also a method of limiting emissions of harmful substances into the atmosphere and meeting strict environmental protection regulations, especially in special areas.

The technology of supplying liquid and gas fuels (Dual Fuel) is most easily used in four-stroke engines but the highest thermal efficiency is ensured by combustion two-stroke piston engines. However, in the first two-stroke dual-fuel engines, the gas supply installation was more complicated than in the four-stroke engine. It resulted, among others from the necessity of compressing the gas to high pressures (15÷30 MPa), for which extremely energy-consuming multi-stage compression systems were needed. The complicated technical system is inherently prone to failures, which is why the dual-fuel low-speed two-stroke diesel engines remained for a long period in the design and experimental phase. In recent years, there has been a significant breakthrough thanks to the introduction of new solutions with the possibility of supplying two-stroke engines with low-pressure gas (less than 1.6 MPa). In recent years, many ships powered by two-stroke, dual-fuel internal combustion engines were commissioned. Some ship-owners owning a fleet of LNG carriers with two-stroke diesel engines that so far have been powered only by liquid fuels have decided to adapt them to gas combustion. This required the adaptation of the engine for gas combustion and the expansion of the supply gas fuel system.

This paper is an attempt to analyse the legitimacy of introducing two-stroke, dual-fuel internal combustion engines into the propulsion system and adaptation of engines that are already used to burn gas in them. It presents the changes introduced on one of the LNG gas carriers consisting in adapting the engine to gas combustion through modification of the cylinder head and fuel supply installation. Parameter results of the modified engines obtained during sea trials have been presented. Both advantages and disadvantages resulting from gas combustion have been pointed out. Finally, the possibility of this solution application to other LNG carriers was assessed.

Schlüsselwörter

  • natural gas
  • LNG carriers
  • low speed 2-stroke dual-fuel engines
Open Access

ISM Code on Vessels With or Without Impact on a Number of Incidents Threats

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 53 - 59

Zusammenfassung

Abstract

It was presented short analysis of connection ISM Code on vessels on the number of incidents threats. Introduced into force ISM Code in 1998 and 2002 (contained in chapter 9 of SOLAS Convention) as obligatory on vessels have had the aim of decreasing the number of injuries, serious injuries, fatalities, other incidents threats and total loses during vessel operation in maritime shipping. The next aim vicariously was improving the maritime safety and prevention of marine pollution from ships. As a result of ship-owner and crew requirements, it should eliminate from shipping market the bad and poor management systems of charterers or ship operators and improper qualified crewmembers. The company and the ship shall comply with the requirements of ISM Code and the company shall have the Document of Compliance (referred to in regulation 4 of ISM Code).

After about twenty years when ISM Code was in force some comparisons, conclusions and remarks were presented. It is observed the decreasing number of vessel total losses but other comparisons is not so clear due to different definitions of incident being obligatory in states of flag and different databases in the different Memoranda of Understanding. The influence of introducing ISM Code on maritime shipping is serious in good or bad matters (e.g. the increasing of bureaucracy).

Schlüsselwörter

  • shipping
  • vessel
  • incident threats
  • fatalities
  • ISM Code
Open Access

Study of Bypass Ratio Increasing Possibility for Turbofan Engine and Turbofan with Inter Turbine Burner

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 61 - 68

Zusammenfassung

Abstract

Current trends in the high bypass ratio turbofan engines development are discussed in the beginning of the paper. Based on this, the state of the art in the contemporary turbofan engines is presented and their change in the last decade is briefly summarized. The main scope of the work is the bypass ratio growth analysis. It is discussed for classical turbofan engine scheme. The next step is presentation of reach this goal by application of an additional combustor located between high and low pressure turbines. The numerical model for fast analysis of bypass ratio grows for both engine kinds are presented. Based on it, the numerical simulation of bypass engine increasing is studied. The assumption to carry out this study is a common core engine. For classical turbofan engine bypass ratio grow is compensated by fan pressure ratio reduction. For inter turbine burner turbofan, bypass grown is compensated by additional energy input into the additional combustor. Presented results are plotted and discussed. The main conclusion is drawing that energy input in to the turbofan aero engine should grow when bypass ratio is growing otherwise the energy should be saved by other engine elements (here fan pressure ratio is decreasing). Presented solution of additional energy input in inter turbine burner allow to eliminate this problem. In studied aspect, this solution not allows to improve engine performance. Specific thrust of such engine grows with bypass ratio rise – this is positive, but specific fuel consumption rise too. Classical turbofan reaches lower specific thrust for higher bypass ratio but its specific fuel consumption is lower too. Specific fuel consumption decreasing is one of the goal set for future aero-engines improvements.

Schlüsselwörter

  • aero engines
  • turbofan engine
  • combustion engines
  • aero engine development
  • turbine inter stage burner
Open Access

Magnetic Memory Inspection of an Overhead Crane Girder – Experimental Verification

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 69 - 76

Zusammenfassung

Abstract

The safety and efficiency of material handling systems involve periodical inspections and evaluation of transportation device technical conditions. That is particularly important in case of industrial cranes, since they are subjected to a large impact load and mechanical stresses acting on the crane's structure and equipment. The paper considers the possibility of a crane structure inspection using the metal magnetic memory (MMM) method. As an advanced non-destructive technique, this method can be employed for inspection of crane structure during operation, which leads to reduce the down time costs and increase the safety confidence in the monitoring process. The MMM technique is effective for early identification of the possible defect location and detecting the micro-damage in ferromagnetic structures through detecting the stress concentration areas. The basic principle of MMM method is the self-magnetic flux leakage signal that correlates with the degree of stress concentration. This method allows detecting early damage of ferromagnetic material through performing measurement in the earth magnetic field, without the use of a special magnetizing device. The paper presents the experimental results carried out on the double-girder overhead travelling crane with hoisting capacity 1000 kg. The influence of the load variation and duration time on the intensity of the self-magnetic flux leakage signal is analysed and discussed.

Schlüsselwörter

  • overhead crane
  • metal magnetic memory method
  • damage detection
Open Access

Quadrotor UAV Control for Transportation of Cable Suspended Payload

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 77 - 84

Zusammenfassung

Abstract

Payload transportation with UAV’s (Unmanned Aerial Vehicles) has become a topic of interest in research with possibilities for a wide range of applications such as transporting emergency equipment to otherwise inaccessible areas. In general, the problem of transporting cable suspended loads lies in the under actuation, which causes oscillations during horizontal transport of the payload. Excessive oscillations increase both the time required to accurately position the payload and may be detrimental to the objects in the workspace or the payload itself. In this article, we present a method to control a quadrotor with a cable suspended payload. While the quadrotor itself is a nonlinear system, the problem of payload transportation with a quadrotor adds additional complexities due to both input coupling and additional under actuation of the system. For simplicity, we fix the quadrotor to a planar motion, giving it a total of 4 degrees of freedom. The quadrotor with the cable suspended payload is modelled using the Euler-Lagrange equations of motion and then partitioned into translation and attitude dynamics. The design methodology is based on simplifying the system by using a variable transformation to decouple the inputs, after which sliding mode control is used for the translational and pendulum dynamics while a feedback linearizing controller is used for the rotational dynamics of the quadrotor. The sliding mode parameters are chosen so stability is guaranteed within a certain region of attraction. Lastly, the results of the numerical simulations created in MATLAB/Simulink are presented to verify the effectiveness of the proposed control strategy.

Schlüsselwörter

  • transport
  • UAV
  • quadrotor
  • under actuated
  • cable suspended payload
  • sliding mode control
Open Access

Analysis of the Application of Distributed Propulsion to the AOS H2 Motor Glider

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 85 - 92

Zusammenfassung

Abstract

The paper describes the selection of a distributed propulsion for the AOS H2 motor glider (selection of engines, their number, and propellers) and determination of its performance. This analysis is related to the research conducted on environment friendly and hybrid propulsions in various research centres. The main aim of the analyses conducted is to increase the performance of vehicles powered by electric motors. The batteries have a low density of energy, i.e. the ratio of mass to cumulated energy. Instead of a battery set, it is possible to apply a hybrid-electric system, where the combustion engine works as a generator or an electric-hydrogen generator, where the hydrogen cell supports a small set of batteries. One of such flying vehicles, fitting in this trend, is the AOS H2 motor glider built at the Rzeszow University of Technology in cooperation with other universities. It is a hybrid aircraft, equipped with a hydrogen cell, which together with a set of batteries is a source of electricity for the Emrax 268 electric motor. To increase the vehicle's performance (the range and flight duration), it is possible to use a distributed propulsion. This type of propulsion consists in placing many electric motors along the wingspan of the aircraft. Appropriate design of such a system (propeller diameters, engine power, number of engines) can improve the aerodynamic and performance parameters of the airframe. An analysis of the performance for the selected flight trajectory for this propulsion variant was conducted and compared to the performance of the AOS H2 motor glider equipped with traditional propulsion. The consumption of hydrogen was also determined for both systems. The results obtained were presented in the diagrams and discussed in the conclusions.

Schlüsselwörter

  • Aircraft Engineering
  • Engines
  • Mechanical Engineering
Open Access

6-Stroke Engine: Thermodynamic Modelling and Design for Testing

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 93 - 106

Zusammenfassung

Abstract

In the study AVL BOOST™ is used to perform a thermodynamic simulation of a six-stroke engine, being built by a research team based in Saudi Arabia. The six-stroke cycle consists of a standard four-stroke Otto Cycle followed by a heat recovering steam expansion cycle. Water is injected into the hot combustion chamber towards the end of the Otto expansion stroke producing steam, which is used to perform work on a piston. This process produces power using waste heat and therefore increases the overall efficiency of the engine. The Robin EY28D engine, which is a single cylinder, four-stroke, gasoline engine was used for this simulation study. The engine was modelled and converted into six-stroke engine in AVL BOOST. The results show that six-stroke engine is more efficient than four-stroke engine. In six-stroke engine, the engine power is increased by 33.1% and brake specific fuel consumption (BSFC) is decreased by approximately 16%. Where emissions are concerned, Nitrogen Oxide (NOx) emission from six-stroke engine is reduced by 80%, while the Hydrocarbon (HC) emission increases by 85% compared with the original 4-stroke. Moreover, the most efficient camshaft was found and designed according to the most efficient valve profile for this engine, which is combination of 60CA° of valve duration and 10 mm of valve lifting.

Schlüsselwörter

  • six-stroke engine
  • water injection
  • steam expansion
  • engine efficiency
  • dynamic gas model
Open Access

Analysis of the Impact of Changes in Flight Speed and Altitude on Emission Indexes of Pollutants in Jet Engine Exhausts

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 107 - 113

Zusammenfassung

Abstract

In currently implemented international aviation strategies and programs, including those realised under the European Union policy, such as Clean Sky, SES, SESAR and, CORSIA, the environmental aspect is particularly prominent – reducing the emission of all gaseous pollutants, and from 2020 also particulate matter. Therefore, it is important to know how the change in flight parameters (altitude, speed) affects the emission of pollutants in jet engine exhausts. Such information will enable to adjust the flight altitude of the aircraft when ecological aspect is taken into consideration. In addition to the operating condition (altitude, flight speed, range of power or thrust), the amount and type of pollutants emitted depends on the type of aircraft, its aerodynamic characteristics, engine type and as well as on the type of fuel used.

The impact of changes in aircraft flight parameters (speed and altitude) on the performance of a bypass jet engine and the emission of pollutants in its exhausts is analysed in the paper. For this purpose, the speed-altitude characteristics of such an engine were determined. Next, the emission indexes (EI) for the LTO phase taken from the ICAO database were used to determine the emission indexes corresponding to given parameters of both the engine operation and the aircraft flight. For selected speeds and cruising altitudes, the value of thrust required for the flight of the aircraft was determined and to this value, the engine operation range was assigned as well the corresponding pollutant emission indexes. This allowed to calculate the mass of pollutants emitted per unit of time for given flight parameters. The results obtained are presented in the graphs and discussed.

Schlüsselwörter

  • aircraft
  • exhausts emission
  • bypass engine
  • emission index
Open Access

Digital Recording Devices is Element of Safety of the Road Transport

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 115 - 120

Zusammenfassung

Abstract

The duty of applying recorders in the road transport was implemented in states of the European Union on regulations (EWG) no. 3820 / 85 on harmonizations of some social welfare legislation referring to the transport, which was changing with regulation (EWG) no. 3821/85 on recorders applied in the road transport. The duty of implementation of the digital tachograph is also considered in the context of improving road safety. Through the analysis of the records of the registering devices can be defined in each specific case of speeding by more than the allowable value in the area. Technical requirements for your device recorded in the resolution, which defines the main parameters, are measured, among things other, the traversed path length of the car, speed, time driving, other periods of work, politeness of the driver and the correct operation of the check authorized for those authorities. At present led Regulation (EU) No 165/2014 of European Parliament establishing requirements concerning structure, checking, installation, use and repairs of tachographs and their building blocks is implementing the second generation of the digital tachographs connected with the device GNSS (Global Navigation Satellite System). Organizing the early detection from a distance is showing data officers from the digital tachograph and information concerning mass and mass falling on the wasp of the entire team of vehicles. Experience in work, economic pressures and competition in transport has led the drivers through a transport company in the event noncompliance, and in particular, in relation to the driving time and breaks. This article contains responsibilities after part rest on the drivers of vehicles takes the issues of system security and optimum performance of recording devices.

Schlüsselwörter

  • transport road
  • card driver
  • digital recorder
  • manipulations digital recorder
Open Access

A Method for Energy Consumption Assessment by Operation of BEV’s in Different Road Conditions

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 121 - 127

Zusammenfassung

Abstract

For the third time in the history of humankind, it is trying to implement e-mobility. There is a reasonable hope that this attempt will succeed this time. E-mobility is generally regarded as a zero emission. This sentence can only be true in a very small scope, as only in relation to selected parameters and in a very limited its dimension. The situation can change radically. If it will be take into account, the emissions in the production of electricity is necessary for the movement of this type of vehicles Second problem is the energy use amount. We know today that the energy consumption of electric cars, especially in long-term operation is too big. This general knowledge is not confirmed by research results. Both relevant databases and methods of their analysis are missing. This is an unfavourable situation because it is not possible to verify the effects of various changes introduced e.g. in the construction or technology of cars. This publication can be included in those in which it is shown how to change this situation.

The analysis of the results of long-term car use can be used as a verification of various development works, especially in e-mobility, which is only just starting. In the future, it will be need to create the appropriate “big data” databases and a number of tools to analyse the data collected there.

Schlüsselwörter

  • transport
  • road transport
  • battery energy vehicles
  • energy consumption
Open Access

Measuring Instruments Used at the Research and Accuracy of Defining the Efficiency of Drive Systems

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 129 - 135

Zusammenfassung

Abstract

The aim of the article is to look at the possibility of accurately determining the energy efficiency of drive systems thanks to the use of high quality sensors and measuring instruments. The types of measuring instruments used on the test stand are presented. The results of experimentally determined efficiencies and simulationally determined efficiencies of two hydrostatic systems with throttling control were compared, which are fed with a constant capacity pump. The choice of the analysed systems is not accidental. There is still a view in the literature about limited possibilities of energy systems with proportional control. The research stand was very carefully designed and made. The applied measuring instruments were characterized by high accuracy of measurements. The issues related to the determination of energy losses and energy efficiency of the engine or drive system, which should be determined as dependent on the physical quantities independent of these losses, were also discussed. For laboratory verification, measurement methods were developed, the test stand was adapted and automated. It consists of tested system and loaded system. The measurements during the tests were saved on the computer disk. In order to be able to compare the efficiency of the overall system with the efficiency obtained on the basis of the simulation, coefficients ki determining the energy losses of individual elements of the system were calculated. The research showed a large convergence of the mathematical description of energy losses in the elements of the system and the efficiency of the system with reality. The mathematical model enables accurate simulation determination of the energy efficiency of the system at each point of its field of operation, i.e. at each speed and load of the controlled hydraulic motor. The range of motor speed and load variation can also be accurately determined simulationally.

Schlüsselwörter

  • energy efficiency
  • accuracy
  • measurements
  • measurement results
  • measuring instruments
Open Access

Simulation of Boundary States of Helicopter Flight

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 137 - 144

Zusammenfassung

Abstract

Results of simulation of main rotor blade loads and deformations, which can be generated during boundary states of helicopter flight, are presented. Concerned cases of flight envelope include hover at maximum height, level flight at high velocity, pull-up manoeuvres applying cyclic pitch and mixed collective and cyclic control. The simulation calculations were executed for data of light helicopter with three-bladed articulated rotor. For analysis, the real blades are treated as elastic axes with distributed masses of blade segments. The model of deformable blade allows for out-of-plane bending, in plane bending, and torsion. For assumed flight state of helicopter, the equations of rotor blades motion are solved applying Runge-Kutta method. According to Galerkin method, for each concerned azimuthal position of blade the parameters of its motions are assumed as a combination of considered bending and torsion eigen modes of the blade. The loads of rotor blades generated during flight depend due to velocity of flight, helicopter mass, position of rotor axis in air and deflections of swashplate that correspond to collective and cyclic pitch angle applied to rotor blades. The results of simulations presenting rotor loads and blade deformations are shown in form of time-runs and as plots of rotor-disk distributions. The simulations of helicopter flight states may be useful for prediction the conditions of flight-tests without exceeding safety boundaries or may help to define limitations for manoeuvre and control of helicopter.

Schlüsselwörter

  • helicopter
  • boundary flight
  • rotor loads
Open Access

Comparison of Image Analysis Methods on the Example of Ultrasonic Thermography of an Aramid Composite

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 145 - 150

Zusammenfassung

Abstract

Infrared thermography using ultrasound thermal excitation of the tested material is one of the most effective methods in non-destructive testing of a multi-layer aramid composite. This type of material is very popular in the construction of light ballistic armours. Typical defects are delamination between layers of aramid fabric joined by resin. They are usually filled with air. Delamination located deep under the surface of the test generates very weak temperature signals. They are often at the level of noise. To reduce the impact of noise on the detection of a defect, special methods of image analysis (thermograms) are used. Such methods include principal component analysis and wavelet analysis. Principal Component Analysis is a relatively new procedure of statistical data treatment, which is becoming increasingly popular in non-destructive testing. Mathematically, it is often regarded as implementation of the so-called singular values decomposition technique, which allows extracting of spatial information from a matrix of source data. The wavelet analysis is an integral transform, which represents the convolution of an analysed process with a special mother function called wavelet. Wavelets are characterized by two parameters: scale and shift. The paper presents a comparison of the efficacy of these methods in the detection of defects in the multilayer composite reinforced aramid fibre.

Schlüsselwörter

  • non-destructive testing
  • composite material
  • IR thermography
  • image analysis
Open Access

Simulations of Hot-Gas Flow in Internally Cooled Cascade of Turbine Vanes

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 151 - 158

Zusammenfassung

Abstract

An experiment in cooling of gas turbine nozzle guide vanes was modelled numerically with a conjugate viscous-flow and solid-material heat conduction solver. The nozzle vanes were arranged in a cascade and operated in high-pressure, hot-temperature conditions, typical for first turbine stage in a flow of controlled-intensity, artificially-generated turbulence. The vane cooling was internal, accomplished by 10 channels in each vane with cooling-air flow. Numerical simulations of the experiment were conducted applying two turbulence models of the k-omega family: k-omega-SST and Transition SST implemented in the ANSYS Fluent solver. Boundary conditions for the simulations were set based on conditions of experiment: total pressures and total temperature on inlet to cascade, static pressure on the outlet of the cascade and heat flux on the surface of cooling channels. The values of heat flux on the surface of cooling channels were evaluated based on Nusselt numbers obtained from experiment and varied in time until steady-state conditions were obtained. Two test cases, one with subcritical outlet flow, and another one, with supercritical outlet flow were simulated. The result of experiment – distributions of pressure, surface temperature, and heat transfer coefficients on the vane external surface were compared to results of numerical simulations. Sensitivity of the vane surface temperatures and heat transfer coefficients to turbulence models and to boundary-condition values of parameters of turbulence models: turbulence energy and specific dissipation of turbulence energy was also studied.

Schlüsselwörter

  • aircraft engines
  • mechanical engineering
  • engine parts
  • simulation and modelling
Open Access

Use of Cryptography Principles in Digital Registration Devices

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 159 - 166

Zusammenfassung

Abstract

Cryptography is a field of science necessary to solve problems with encryption of classified messages. The security of electronic information is an integral part of the digital tachography system. From year to year, there is a noticeable increase in electronic data logging systems in many aspects of life. The control measures created for the purpose of performing roadside checks are not sufficient to detect all violations in the recording equipment. Many violations that have occurred during the use of the vehicle are stored in the device’s memory. The article describes the basic mathematical rules illuminating cryptography. The hazards to which the motion sensor installed in the vehicle may be exposed are described. Breaking safety in transport systems may lead to incorrect results of inspections carried out while the vehicle is stopped by authorized services. The article also provides information on the authorities responsible for issuing cards for digital tachographs. Nowadays, documents are increasingly issued with the use of a digital signature. The digital signature of its origin is based on the principles of cryptography. The security key seems to be complicated for the average user. The article discusses the topic of tachograph construction, in particular the schematic responsible for information encryption.

Schlüsselwörter

  • tachograph cards
  • cryptography
  • digital tachograph system
  • recording equipment
  • road transport
Open Access

Estimation of Random Friction Forces on the Microbearing Cooperating Surfaces

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 167 - 174

Zusammenfassung

Abstract

Presented paper concerns a new mathematical form of stochastic theory of hydrodynamic friction forces occurring on the real cooperating surfaces in computer micro bearing fan and computer microbearing in hard disc driver HDD. This paper presents particularly a new-review of stochastic analytical considerations realized by the authors for friction forces estimation during hydrodynamic lubrication performed on the ground of the measurements of the gap height between two roughness surfaces. After numerous experimental measurements directly follows that the random unsymmetrical increments and decrements of the gap height of computer microbearings have important influence on the load carrying capacities and finally on the friction forces and wear of cooperating surfaces. The main topic demonstrates the influence of the variations of expectancy values and standard deviation of the computer microbearing gap height on the friction forces occurring in the HDD and microbearing fan. Moreover, it is observed the evident connection between the apparent dynamic viscosity and the features of the microbearing superficial surface. Hence after abovementioned remarks follows the corollary that the influence of the microbearing gap height stochastic variations connected with the surface roughness tend moreover indirect from the apparent viscosity into the friction forces variations. The synthetic, complex elaboration of obtained results indicates finally the influence of the random roughness in micro and nano level of microbearing surfaces on the friction forces distribution. A new results contained in this paper are obtained taking into account 3D variations of dynamic viscosity of the non-Newtonian lubricant, particularly variations crosswise the film thickness and influences of surface superficial layer features on the lubricant apparent viscosity.

Schlüsselwörter

  • microbearings
  • computer fan
  • hard disc driver bearings
  • hydrodynamic lubrication
  • analytical stochastic principles
  • analytical solutions
  • apparent viscosity depended on the gap height variations
Open Access

Stability of Wheeled Armoured Personnel Carrier Firing Sideways

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 175 - 180

Zusammenfassung

Abstract

One of the most important and commonly used means of transport in the armed forces of various countries is wheeled armoured personnel carriers. After proper preparation, beside transport tasks, they can carry out special tasks, as part of regular and irregular activities within purpose of supporting actions of troops. This paper presents preliminary results of numerical research of wheeled armoured personnel carrier with 8x8-drive system. The effect of impact of large calibre cannon (120 mm) with reduced recoil force on transporter behaviour was investigated. The research object model consists of shell, solid and discrete elements. The research was carried out in the LS-DYNA software. Considered variant applies to sideways firing (to the left of the vehicle) for cannon elevation angle 16 deg. Numerical model of standing still on the flat ground wheeled armoured personnel carrier was preloaded with the gravitational force. The results of post-firing vehicle behaviour including angular displacement of the hull, dynamic deflections of the suspensions and impact on the stability of the wheeled vehicle were evaluated.

Schlüsselwörter

  • wheeled vehicle
  • vehicle dynamics
  • vehicle stability
  • armament
  • finite element method
Open Access

The Impact of a Place for the Measurement of Cylinder Pressure of Marine Piston Engine on the Indicator Diagrams and Indicator Parameters

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 181 - 188

Zusammenfassung

Abstract

The article discusses one of the most popular methods of diagnosing selected damages of marine piston engines, which is the indication or measurement of pressure changes in the engine’s combustion chamber. Improving the quality of indicator diagrams may contribute to the increase in the efficiency of using the parameters indicated in the diagnostics of marine piston engines. Measurement errors during engine indication are primarily caused by measuring channels that connect the combustion chamber to the pressure sensor. One way to avoid these errors is to install the pressure sensor directly in the combustion chamber. It seems that it is possible to eliminate these errors. However, there is a risk that the pressure sensor will be damaged by the effect of high temperature on it during combustion of the fuel-air mixture in the engine’s combustion chamber. The article presents the results of tests that indicate that the measured temperatures in the place where the sensor was installed (in the combustion chamber) did not exceed the critical value specified by the pressure sensor manufacturer. The article also presents the results of cylinder pressure measurement not only in the combustion chamber but also in two other points - on the thread of the indicator cock and in the measuring channel between the indicator cock and the cylinder head. The tests were carried out in a wide range of engine load technically efficient and with simulated damage in the fuel injection system. The article presents a comparative analysis of the parameters read out of the indicator diagram for the three above-mentioned pressure measurement locations. It was shown that the pressure measurements carried out directly in the combustion chamber are free from errors resulting from the influence of measuring channels and indicator cock.

Schlüsselwörter

  • diagnostics
  • marine piston engines
  • self-ignition engines
  • indication
  • middle indicated pressure
  • combustion pressure
Open Access

Influence of Seawater Salinity on Corrosion of Hull Structural Steel

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 189 - 195

Zusammenfassung

Abstract

Hulls of ships are often made of steel, which are produced under the supervision of classification societies. Usually, the hull steel of ordinary strength category A is used for the ship's shell (the yield strength is 235 MPa and the impact strength 27 J at 20ºC). Vessels sail in sea areas with various levels of salinity and thus with different corrosiveness. The average salinity of the seas is taken as 3.5% content of sodium chloride. This article presents the results of corrosion tests of S235 JRG1 steel in an aqueous solution in which the mass fraction of sodium chloride was: 0.7%, 1.4%, 2.2%, 2.8%, 3.5% and 4.2%. Corrosion tests were performed using the potentiodynamic method. As parameters characterizing the corrosion properties of the tested steel, the corrosion current density and corrosion potential were assumed. Statistically significant influence of seawater salinity on the corrosion properties of hull structural steel of ordinary strength of category A was found. The highest value of the corrosion current density was observed in the solution containing 3.5% NaCl mass fraction was observed. In seawater with a sodium chloride content in the range of 0.7 to 3.5%, an increase in the value of the corrosion current density was observed, along with the increasing share of NaCl. In seawater with higher salinity, the corrosion rate was reduced. The corrosion potential of S235JRG1 steel decreases with the NaCl content in the corrosive solution. The susceptibility of this material to corrosion in seawater increased.

Schlüsselwörter

  • hull structural steel
  • corrosion
  • potentiodynamic test
  • seawater
Open Access

Inverse Problem of Selection of the Theoretical Cycle for the Real Cycle of Internal Combustion Engine

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 197 - 204

Zusammenfassung

Abstract

The effectiveness of work of an internal combustion engine can be assessed by means of the energy efficiency: theoretical, internal and effective... In the problem regarding the efficiency of obtaining a work from the tested SI engine, the theoretical Seiliger-Sabathe cycle was adopted as a reference model for the real engine cycle. For comparison, the OTTO cycle was also analysed. The engine indicating allows direct determination only of internal work. However, determining the work of the theoretical cycle first requires solving the problem of selecting the parameters of the theoretical cycle, according to the real cycle of the engine (inverse problem). In order uniquely to determine the course of the theoretical Seiliger-Sabathe cycle, it is necessary to determine the parameters of the starting point and the heat distribution number. The selection of the theoretical cycle for the real cycle, within the scope of determining the number of heat distribution, is to some extent of a contractual nature. Therefore, the problem of determining the number of heat distribution was solved by two own original methods. A comparison of the real cycle with the theoretical cycle determined for it is presented.

Schlüsselwörter

  • internal combustion engine
  • real cycle
  • theoretic cycle
  • heat distribution number
  • the reconciliation algorithm
25 Artikel
Open Access

Influence of the Cyclic Hardening Model on the Results of the Numerical Analysis of Fatigue Life on Example of the Compressor Blade

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 7 - 14

Zusammenfassung

Abstract

The main goal of the presented work is to determine the impact of the cyclic hardening model on the numerical results of the ε-N fatigue test. As an object of study, compressor blade (from PZL-10W helicopter engine) was used. The examined blade was made of EI-961 alloy. In numerical analysis, a geometrical model of the blade with a preliminary defect was created. Geometrical defect – V-notch was created on the leading edge. This defect was introduced in order to weaken the structure of the element and the possibility of observing the crack initiation process (in experimental tests). Material data to ε-N analysis, based on Manson-Coffin-Basquin equation, were estimated for Mitchell’s model. This model was built based on strength data provided by the steel producer. Based on three different models of cyclic hardening (Manson, Fatemi, and Xianxin), a number of load cycles were calculated. Load cycle during numerical analysis was represented as resonance bending with an amplitude of displacement equal to A = 1.8 mm. Obtained results were compared with experimental data. Additionally, the analytical model of ε-N fatigue (depending on the cyclic hardening) was prepared. All the work carried out has been summarized by a comprehensive comparative analysis of the results. Obtained results and dependencies can be used in the selection of an appropriate model of cyclic hardening in further fatigue tests of many aerospace elements.

Schlüsselwörter

  • fatigue life
  • compressor blade
  • aircraft engine
  • cyclic hardening
  • numerical analysis
Open Access

Properties of AlMg3 Aluminium Alloy Joints Welded by Electron Beam Melting

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 15 - 20

Zusammenfassung

Abstract

Electron beam welding, called electron welding consists in penetrating the elements being welded with heat obtained from the elements’ bombardment in vacuum with concentrated electron beam of high energy. Concentration of the electron beam of high kinetic energy in a very small space results in generating the heat of high concentration causing melting of material in high depth. During the metal melting the electron beam makes a narrow weld of little heat affected zone (HAZ). This paper presents the test results on selection of parameters of electron beam welding of 12 mm thickness sheets of AlMg3 aluminum alloy. The beam electron melting through was carried out in vacuum by means of the welding machine WS-15 KW/100 KV. Before melting, the sheets were degreased in tetrachloroethylene and oxides were removed with 15% solution Na2Co3. The influence of electron beam melting through of sheets on their mechanical properties was tested as well as resistance to stress corrosion cracking and resistance to corrosion in fast seawater flow (10 m/s). The slow strain rate stress corrosion tests in the air and artificial seawater were performed. It was found that electron beam melting through of the AlMg3 alloy does not decrease the mechanical properties in comparison to the native material. The crack during the static tension test had ductile character and proceeded in the native material. AlMg3 alloy melting with electron beam shows a very good stress corrosion resistance.

Schlüsselwörter

  • electron beam welding
  • aluminium alloy
  • stress corrosion
Open Access

The Possibility of Applying Acoustic Emission Method for Monitoring Lathing Process

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 21 - 27

Zusammenfassung

Abstract

Nowadays acoustic emission (AE) method is used in many fields of science, including in the diagnosis and monitoring of machining processes such as turning, grinding, milling, etc. Monitoring of turning process allows ensuring stable conditions of treatment. Stable conditions of turning process have a great impact on the quality of the surface. This is especially important during finishing treatment.

The research was carried out on a universal ZMM-SLIVEN CU500MRD lathe centre-using tool with removable insert SANDVIK Coromant WNMG 080408 – WMX Wiper. Lathing process was performed on the shaft of 74 mm in diameter made of S235 steel.

The research was carried out at constant cutting speed v = 230 m/min. Changed parameters were feed f = 0.1; 0.2; 0.4 mm/rev and cutting depth ap = 0.5; 0.75; 1 mm. In the research was used a set of acoustic emission Vallen System. The kit includes: 4 channel signal recorder AMSY 6, two measurement modules ASIP-2/S, preamplifier with a frequency range 20 kHz – 1 MHz and the strengthening of 34dB and AE signal measurement sensor type VS 150M, with a frequency range 100 – 450 kHz. During the study, the acoustic emission (AE) generated during the lathing process were recorded parameters e.g. amplitude, number of events – hits, the effective value of the signal (RMS).

The test results indicate, that the higher instability of the process was during turning with parameters: ap = 0.75 mm and f = 0.1 mm/rev. The study can be the basis for the use of acoustic emission method for monitoring lathing process to ensure stable conditions of that process and the same to obtain a high quality surface.

Schlüsselwörter

  • Acoustic Emission (AE)
  • diagnostic
  • finishing treatment
  • lathing
  • cutting parameters
Open Access

The Effect of Parameters and Geometry Cutting Edge After Turning of the Duplex Cast Steel on the Maximum Tool Flank Wear

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 29 - 35

Zusammenfassung

Abstract

It is important to shape the required properties of the surface layer in the technological process. This issue is an important problem due to the ability of the kinematic pair elements to the required reliable operation of machine parts. The latest generation devices work with increasing operational loads. This forces the search forever-newer construction materials or innovative manufacturing engineering technologies that would ensure high reliability and durability of machine components. For mechanical engineering, continue to be used on steel structures of machine parts. In the petrochemical and shipbuilding industry, stainless steels are very poplars. Those materials are used in the constructions of seawater and acid installations. Currently, a newer material with more favourable properties is two-phase stainless steel. This is the so-called duplex steel. It can be applied to pump shafts in acid or seawater solutions. Duplex cast steel is a difficult-to-cut material. It is important to determine the effect of cutting parameters on the surface quality of the shafts and wear of cutting edge. Traditional methods of finishing surface treatment of shafts are machining (turning, grinding, superfinishing). Considering the possibilities of equipping a marine power plant workshop, it would be best to use machining by turning.

The paper specifies the relationship between the wear of the cutting edge and the geometrical structure of the machined surface as well as the type of tool material used and the shape of the cutting inserts.

Schlüsselwörter

  • turning
  • surface roughness
  • duplex cast steel
  • cutting edge
  • flank wear
Open Access

Impact of Processing Parameters on Surface Roughness and Strain Hardening of Two-Phase Stainless Steel

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 37 - 44

Zusammenfassung

Abstract

Products used in the construction of machines and shipbuilding as well as petrochemical industry, such as shafts, bars, pipes and the like from two-phase stainless steel are currently very popular. It is required that they meet certain quality criteria. They must be characterized by suitable properties of the surface layer to meet the requirements of potential buyers.

In the article impact of processing parameters on the degree of relative strain hardening and index of surface roughness reduction were presented. The burnishing process was carried out for two-phase stainless steel. Burnishing process of the shafts neck was performed using burnisher roller. The experimental research were obtained in the surface layer increase in hardness and the material ratio curve a convex shaped, which, taking into account the load capacity of the surface will be directly affected by its resistance to wear and corrosion. The experimental research by application of the burnishing process was made in the Laboratory of Production Engineering. After the studies it was found that the hardness of the surface layer and the roughness of the shaft necks an important influenced by technological parameters of processing (burnishing speed, feed rate and depth of burnishing). The objective of applying burnishing process may be, for example, the need to increase surface smoothness and dimensional accuracy of part.

Schlüsselwörter

  • burnishing process
  • index of surface roughness reduction
  • degree of relative strain hardening
  • two-phase stainless steel
Open Access

Analysis of the Possibility of Using Low Speed Two-Stroke Dual-Fuel Engines for Propulsion of Sea-Going Vessels

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 45 - 52

Zusammenfassung

Abstract

The use of gas/LNG to supply marine engines in addition to tangible economic benefits is also a method of limiting emissions of harmful substances into the atmosphere and meeting strict environmental protection regulations, especially in special areas.

The technology of supplying liquid and gas fuels (Dual Fuel) is most easily used in four-stroke engines but the highest thermal efficiency is ensured by combustion two-stroke piston engines. However, in the first two-stroke dual-fuel engines, the gas supply installation was more complicated than in the four-stroke engine. It resulted, among others from the necessity of compressing the gas to high pressures (15÷30 MPa), for which extremely energy-consuming multi-stage compression systems were needed. The complicated technical system is inherently prone to failures, which is why the dual-fuel low-speed two-stroke diesel engines remained for a long period in the design and experimental phase. In recent years, there has been a significant breakthrough thanks to the introduction of new solutions with the possibility of supplying two-stroke engines with low-pressure gas (less than 1.6 MPa). In recent years, many ships powered by two-stroke, dual-fuel internal combustion engines were commissioned. Some ship-owners owning a fleet of LNG carriers with two-stroke diesel engines that so far have been powered only by liquid fuels have decided to adapt them to gas combustion. This required the adaptation of the engine for gas combustion and the expansion of the supply gas fuel system.

This paper is an attempt to analyse the legitimacy of introducing two-stroke, dual-fuel internal combustion engines into the propulsion system and adaptation of engines that are already used to burn gas in them. It presents the changes introduced on one of the LNG gas carriers consisting in adapting the engine to gas combustion through modification of the cylinder head and fuel supply installation. Parameter results of the modified engines obtained during sea trials have been presented. Both advantages and disadvantages resulting from gas combustion have been pointed out. Finally, the possibility of this solution application to other LNG carriers was assessed.

Schlüsselwörter

  • natural gas
  • LNG carriers
  • low speed 2-stroke dual-fuel engines
Open Access

ISM Code on Vessels With or Without Impact on a Number of Incidents Threats

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 53 - 59

Zusammenfassung

Abstract

It was presented short analysis of connection ISM Code on vessels on the number of incidents threats. Introduced into force ISM Code in 1998 and 2002 (contained in chapter 9 of SOLAS Convention) as obligatory on vessels have had the aim of decreasing the number of injuries, serious injuries, fatalities, other incidents threats and total loses during vessel operation in maritime shipping. The next aim vicariously was improving the maritime safety and prevention of marine pollution from ships. As a result of ship-owner and crew requirements, it should eliminate from shipping market the bad and poor management systems of charterers or ship operators and improper qualified crewmembers. The company and the ship shall comply with the requirements of ISM Code and the company shall have the Document of Compliance (referred to in regulation 4 of ISM Code).

After about twenty years when ISM Code was in force some comparisons, conclusions and remarks were presented. It is observed the decreasing number of vessel total losses but other comparisons is not so clear due to different definitions of incident being obligatory in states of flag and different databases in the different Memoranda of Understanding. The influence of introducing ISM Code on maritime shipping is serious in good or bad matters (e.g. the increasing of bureaucracy).

Schlüsselwörter

  • shipping
  • vessel
  • incident threats
  • fatalities
  • ISM Code
Open Access

Study of Bypass Ratio Increasing Possibility for Turbofan Engine and Turbofan with Inter Turbine Burner

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 61 - 68

Zusammenfassung

Abstract

Current trends in the high bypass ratio turbofan engines development are discussed in the beginning of the paper. Based on this, the state of the art in the contemporary turbofan engines is presented and their change in the last decade is briefly summarized. The main scope of the work is the bypass ratio growth analysis. It is discussed for classical turbofan engine scheme. The next step is presentation of reach this goal by application of an additional combustor located between high and low pressure turbines. The numerical model for fast analysis of bypass ratio grows for both engine kinds are presented. Based on it, the numerical simulation of bypass engine increasing is studied. The assumption to carry out this study is a common core engine. For classical turbofan engine bypass ratio grow is compensated by fan pressure ratio reduction. For inter turbine burner turbofan, bypass grown is compensated by additional energy input into the additional combustor. Presented results are plotted and discussed. The main conclusion is drawing that energy input in to the turbofan aero engine should grow when bypass ratio is growing otherwise the energy should be saved by other engine elements (here fan pressure ratio is decreasing). Presented solution of additional energy input in inter turbine burner allow to eliminate this problem. In studied aspect, this solution not allows to improve engine performance. Specific thrust of such engine grows with bypass ratio rise – this is positive, but specific fuel consumption rise too. Classical turbofan reaches lower specific thrust for higher bypass ratio but its specific fuel consumption is lower too. Specific fuel consumption decreasing is one of the goal set for future aero-engines improvements.

Schlüsselwörter

  • aero engines
  • turbofan engine
  • combustion engines
  • aero engine development
  • turbine inter stage burner
Open Access

Magnetic Memory Inspection of an Overhead Crane Girder – Experimental Verification

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 69 - 76

Zusammenfassung

Abstract

The safety and efficiency of material handling systems involve periodical inspections and evaluation of transportation device technical conditions. That is particularly important in case of industrial cranes, since they are subjected to a large impact load and mechanical stresses acting on the crane's structure and equipment. The paper considers the possibility of a crane structure inspection using the metal magnetic memory (MMM) method. As an advanced non-destructive technique, this method can be employed for inspection of crane structure during operation, which leads to reduce the down time costs and increase the safety confidence in the monitoring process. The MMM technique is effective for early identification of the possible defect location and detecting the micro-damage in ferromagnetic structures through detecting the stress concentration areas. The basic principle of MMM method is the self-magnetic flux leakage signal that correlates with the degree of stress concentration. This method allows detecting early damage of ferromagnetic material through performing measurement in the earth magnetic field, without the use of a special magnetizing device. The paper presents the experimental results carried out on the double-girder overhead travelling crane with hoisting capacity 1000 kg. The influence of the load variation and duration time on the intensity of the self-magnetic flux leakage signal is analysed and discussed.

Schlüsselwörter

  • overhead crane
  • metal magnetic memory method
  • damage detection
Open Access

Quadrotor UAV Control for Transportation of Cable Suspended Payload

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 77 - 84

Zusammenfassung

Abstract

Payload transportation with UAV’s (Unmanned Aerial Vehicles) has become a topic of interest in research with possibilities for a wide range of applications such as transporting emergency equipment to otherwise inaccessible areas. In general, the problem of transporting cable suspended loads lies in the under actuation, which causes oscillations during horizontal transport of the payload. Excessive oscillations increase both the time required to accurately position the payload and may be detrimental to the objects in the workspace or the payload itself. In this article, we present a method to control a quadrotor with a cable suspended payload. While the quadrotor itself is a nonlinear system, the problem of payload transportation with a quadrotor adds additional complexities due to both input coupling and additional under actuation of the system. For simplicity, we fix the quadrotor to a planar motion, giving it a total of 4 degrees of freedom. The quadrotor with the cable suspended payload is modelled using the Euler-Lagrange equations of motion and then partitioned into translation and attitude dynamics. The design methodology is based on simplifying the system by using a variable transformation to decouple the inputs, after which sliding mode control is used for the translational and pendulum dynamics while a feedback linearizing controller is used for the rotational dynamics of the quadrotor. The sliding mode parameters are chosen so stability is guaranteed within a certain region of attraction. Lastly, the results of the numerical simulations created in MATLAB/Simulink are presented to verify the effectiveness of the proposed control strategy.

Schlüsselwörter

  • transport
  • UAV
  • quadrotor
  • under actuated
  • cable suspended payload
  • sliding mode control
Open Access

Analysis of the Application of Distributed Propulsion to the AOS H2 Motor Glider

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 85 - 92

Zusammenfassung

Abstract

The paper describes the selection of a distributed propulsion for the AOS H2 motor glider (selection of engines, their number, and propellers) and determination of its performance. This analysis is related to the research conducted on environment friendly and hybrid propulsions in various research centres. The main aim of the analyses conducted is to increase the performance of vehicles powered by electric motors. The batteries have a low density of energy, i.e. the ratio of mass to cumulated energy. Instead of a battery set, it is possible to apply a hybrid-electric system, where the combustion engine works as a generator or an electric-hydrogen generator, where the hydrogen cell supports a small set of batteries. One of such flying vehicles, fitting in this trend, is the AOS H2 motor glider built at the Rzeszow University of Technology in cooperation with other universities. It is a hybrid aircraft, equipped with a hydrogen cell, which together with a set of batteries is a source of electricity for the Emrax 268 electric motor. To increase the vehicle's performance (the range and flight duration), it is possible to use a distributed propulsion. This type of propulsion consists in placing many electric motors along the wingspan of the aircraft. Appropriate design of such a system (propeller diameters, engine power, number of engines) can improve the aerodynamic and performance parameters of the airframe. An analysis of the performance for the selected flight trajectory for this propulsion variant was conducted and compared to the performance of the AOS H2 motor glider equipped with traditional propulsion. The consumption of hydrogen was also determined for both systems. The results obtained were presented in the diagrams and discussed in the conclusions.

Schlüsselwörter

  • Aircraft Engineering
  • Engines
  • Mechanical Engineering
Open Access

6-Stroke Engine: Thermodynamic Modelling and Design for Testing

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 93 - 106

Zusammenfassung

Abstract

In the study AVL BOOST™ is used to perform a thermodynamic simulation of a six-stroke engine, being built by a research team based in Saudi Arabia. The six-stroke cycle consists of a standard four-stroke Otto Cycle followed by a heat recovering steam expansion cycle. Water is injected into the hot combustion chamber towards the end of the Otto expansion stroke producing steam, which is used to perform work on a piston. This process produces power using waste heat and therefore increases the overall efficiency of the engine. The Robin EY28D engine, which is a single cylinder, four-stroke, gasoline engine was used for this simulation study. The engine was modelled and converted into six-stroke engine in AVL BOOST. The results show that six-stroke engine is more efficient than four-stroke engine. In six-stroke engine, the engine power is increased by 33.1% and brake specific fuel consumption (BSFC) is decreased by approximately 16%. Where emissions are concerned, Nitrogen Oxide (NOx) emission from six-stroke engine is reduced by 80%, while the Hydrocarbon (HC) emission increases by 85% compared with the original 4-stroke. Moreover, the most efficient camshaft was found and designed according to the most efficient valve profile for this engine, which is combination of 60CA° of valve duration and 10 mm of valve lifting.

Schlüsselwörter

  • six-stroke engine
  • water injection
  • steam expansion
  • engine efficiency
  • dynamic gas model
Open Access

Analysis of the Impact of Changes in Flight Speed and Altitude on Emission Indexes of Pollutants in Jet Engine Exhausts

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 107 - 113

Zusammenfassung

Abstract

In currently implemented international aviation strategies and programs, including those realised under the European Union policy, such as Clean Sky, SES, SESAR and, CORSIA, the environmental aspect is particularly prominent – reducing the emission of all gaseous pollutants, and from 2020 also particulate matter. Therefore, it is important to know how the change in flight parameters (altitude, speed) affects the emission of pollutants in jet engine exhausts. Such information will enable to adjust the flight altitude of the aircraft when ecological aspect is taken into consideration. In addition to the operating condition (altitude, flight speed, range of power or thrust), the amount and type of pollutants emitted depends on the type of aircraft, its aerodynamic characteristics, engine type and as well as on the type of fuel used.

The impact of changes in aircraft flight parameters (speed and altitude) on the performance of a bypass jet engine and the emission of pollutants in its exhausts is analysed in the paper. For this purpose, the speed-altitude characteristics of such an engine were determined. Next, the emission indexes (EI) for the LTO phase taken from the ICAO database were used to determine the emission indexes corresponding to given parameters of both the engine operation and the aircraft flight. For selected speeds and cruising altitudes, the value of thrust required for the flight of the aircraft was determined and to this value, the engine operation range was assigned as well the corresponding pollutant emission indexes. This allowed to calculate the mass of pollutants emitted per unit of time for given flight parameters. The results obtained are presented in the graphs and discussed.

Schlüsselwörter

  • aircraft
  • exhausts emission
  • bypass engine
  • emission index
Open Access

Digital Recording Devices is Element of Safety of the Road Transport

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 115 - 120

Zusammenfassung

Abstract

The duty of applying recorders in the road transport was implemented in states of the European Union on regulations (EWG) no. 3820 / 85 on harmonizations of some social welfare legislation referring to the transport, which was changing with regulation (EWG) no. 3821/85 on recorders applied in the road transport. The duty of implementation of the digital tachograph is also considered in the context of improving road safety. Through the analysis of the records of the registering devices can be defined in each specific case of speeding by more than the allowable value in the area. Technical requirements for your device recorded in the resolution, which defines the main parameters, are measured, among things other, the traversed path length of the car, speed, time driving, other periods of work, politeness of the driver and the correct operation of the check authorized for those authorities. At present led Regulation (EU) No 165/2014 of European Parliament establishing requirements concerning structure, checking, installation, use and repairs of tachographs and their building blocks is implementing the second generation of the digital tachographs connected with the device GNSS (Global Navigation Satellite System). Organizing the early detection from a distance is showing data officers from the digital tachograph and information concerning mass and mass falling on the wasp of the entire team of vehicles. Experience in work, economic pressures and competition in transport has led the drivers through a transport company in the event noncompliance, and in particular, in relation to the driving time and breaks. This article contains responsibilities after part rest on the drivers of vehicles takes the issues of system security and optimum performance of recording devices.

Schlüsselwörter

  • transport road
  • card driver
  • digital recorder
  • manipulations digital recorder
Open Access

A Method for Energy Consumption Assessment by Operation of BEV’s in Different Road Conditions

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 121 - 127

Zusammenfassung

Abstract

For the third time in the history of humankind, it is trying to implement e-mobility. There is a reasonable hope that this attempt will succeed this time. E-mobility is generally regarded as a zero emission. This sentence can only be true in a very small scope, as only in relation to selected parameters and in a very limited its dimension. The situation can change radically. If it will be take into account, the emissions in the production of electricity is necessary for the movement of this type of vehicles Second problem is the energy use amount. We know today that the energy consumption of electric cars, especially in long-term operation is too big. This general knowledge is not confirmed by research results. Both relevant databases and methods of their analysis are missing. This is an unfavourable situation because it is not possible to verify the effects of various changes introduced e.g. in the construction or technology of cars. This publication can be included in those in which it is shown how to change this situation.

The analysis of the results of long-term car use can be used as a verification of various development works, especially in e-mobility, which is only just starting. In the future, it will be need to create the appropriate “big data” databases and a number of tools to analyse the data collected there.

Schlüsselwörter

  • transport
  • road transport
  • battery energy vehicles
  • energy consumption
Open Access

Measuring Instruments Used at the Research and Accuracy of Defining the Efficiency of Drive Systems

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 129 - 135

Zusammenfassung

Abstract

The aim of the article is to look at the possibility of accurately determining the energy efficiency of drive systems thanks to the use of high quality sensors and measuring instruments. The types of measuring instruments used on the test stand are presented. The results of experimentally determined efficiencies and simulationally determined efficiencies of two hydrostatic systems with throttling control were compared, which are fed with a constant capacity pump. The choice of the analysed systems is not accidental. There is still a view in the literature about limited possibilities of energy systems with proportional control. The research stand was very carefully designed and made. The applied measuring instruments were characterized by high accuracy of measurements. The issues related to the determination of energy losses and energy efficiency of the engine or drive system, which should be determined as dependent on the physical quantities independent of these losses, were also discussed. For laboratory verification, measurement methods were developed, the test stand was adapted and automated. It consists of tested system and loaded system. The measurements during the tests were saved on the computer disk. In order to be able to compare the efficiency of the overall system with the efficiency obtained on the basis of the simulation, coefficients ki determining the energy losses of individual elements of the system were calculated. The research showed a large convergence of the mathematical description of energy losses in the elements of the system and the efficiency of the system with reality. The mathematical model enables accurate simulation determination of the energy efficiency of the system at each point of its field of operation, i.e. at each speed and load of the controlled hydraulic motor. The range of motor speed and load variation can also be accurately determined simulationally.

Schlüsselwörter

  • energy efficiency
  • accuracy
  • measurements
  • measurement results
  • measuring instruments
Open Access

Simulation of Boundary States of Helicopter Flight

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 137 - 144

Zusammenfassung

Abstract

Results of simulation of main rotor blade loads and deformations, which can be generated during boundary states of helicopter flight, are presented. Concerned cases of flight envelope include hover at maximum height, level flight at high velocity, pull-up manoeuvres applying cyclic pitch and mixed collective and cyclic control. The simulation calculations were executed for data of light helicopter with three-bladed articulated rotor. For analysis, the real blades are treated as elastic axes with distributed masses of blade segments. The model of deformable blade allows for out-of-plane bending, in plane bending, and torsion. For assumed flight state of helicopter, the equations of rotor blades motion are solved applying Runge-Kutta method. According to Galerkin method, for each concerned azimuthal position of blade the parameters of its motions are assumed as a combination of considered bending and torsion eigen modes of the blade. The loads of rotor blades generated during flight depend due to velocity of flight, helicopter mass, position of rotor axis in air and deflections of swashplate that correspond to collective and cyclic pitch angle applied to rotor blades. The results of simulations presenting rotor loads and blade deformations are shown in form of time-runs and as plots of rotor-disk distributions. The simulations of helicopter flight states may be useful for prediction the conditions of flight-tests without exceeding safety boundaries or may help to define limitations for manoeuvre and control of helicopter.

Schlüsselwörter

  • helicopter
  • boundary flight
  • rotor loads
Open Access

Comparison of Image Analysis Methods on the Example of Ultrasonic Thermography of an Aramid Composite

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 145 - 150

Zusammenfassung

Abstract

Infrared thermography using ultrasound thermal excitation of the tested material is one of the most effective methods in non-destructive testing of a multi-layer aramid composite. This type of material is very popular in the construction of light ballistic armours. Typical defects are delamination between layers of aramid fabric joined by resin. They are usually filled with air. Delamination located deep under the surface of the test generates very weak temperature signals. They are often at the level of noise. To reduce the impact of noise on the detection of a defect, special methods of image analysis (thermograms) are used. Such methods include principal component analysis and wavelet analysis. Principal Component Analysis is a relatively new procedure of statistical data treatment, which is becoming increasingly popular in non-destructive testing. Mathematically, it is often regarded as implementation of the so-called singular values decomposition technique, which allows extracting of spatial information from a matrix of source data. The wavelet analysis is an integral transform, which represents the convolution of an analysed process with a special mother function called wavelet. Wavelets are characterized by two parameters: scale and shift. The paper presents a comparison of the efficacy of these methods in the detection of defects in the multilayer composite reinforced aramid fibre.

Schlüsselwörter

  • non-destructive testing
  • composite material
  • IR thermography
  • image analysis
Open Access

Simulations of Hot-Gas Flow in Internally Cooled Cascade of Turbine Vanes

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 151 - 158

Zusammenfassung

Abstract

An experiment in cooling of gas turbine nozzle guide vanes was modelled numerically with a conjugate viscous-flow and solid-material heat conduction solver. The nozzle vanes were arranged in a cascade and operated in high-pressure, hot-temperature conditions, typical for first turbine stage in a flow of controlled-intensity, artificially-generated turbulence. The vane cooling was internal, accomplished by 10 channels in each vane with cooling-air flow. Numerical simulations of the experiment were conducted applying two turbulence models of the k-omega family: k-omega-SST and Transition SST implemented in the ANSYS Fluent solver. Boundary conditions for the simulations were set based on conditions of experiment: total pressures and total temperature on inlet to cascade, static pressure on the outlet of the cascade and heat flux on the surface of cooling channels. The values of heat flux on the surface of cooling channels were evaluated based on Nusselt numbers obtained from experiment and varied in time until steady-state conditions were obtained. Two test cases, one with subcritical outlet flow, and another one, with supercritical outlet flow were simulated. The result of experiment – distributions of pressure, surface temperature, and heat transfer coefficients on the vane external surface were compared to results of numerical simulations. Sensitivity of the vane surface temperatures and heat transfer coefficients to turbulence models and to boundary-condition values of parameters of turbulence models: turbulence energy and specific dissipation of turbulence energy was also studied.

Schlüsselwörter

  • aircraft engines
  • mechanical engineering
  • engine parts
  • simulation and modelling
Open Access

Use of Cryptography Principles in Digital Registration Devices

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 159 - 166

Zusammenfassung

Abstract

Cryptography is a field of science necessary to solve problems with encryption of classified messages. The security of electronic information is an integral part of the digital tachography system. From year to year, there is a noticeable increase in electronic data logging systems in many aspects of life. The control measures created for the purpose of performing roadside checks are not sufficient to detect all violations in the recording equipment. Many violations that have occurred during the use of the vehicle are stored in the device’s memory. The article describes the basic mathematical rules illuminating cryptography. The hazards to which the motion sensor installed in the vehicle may be exposed are described. Breaking safety in transport systems may lead to incorrect results of inspections carried out while the vehicle is stopped by authorized services. The article also provides information on the authorities responsible for issuing cards for digital tachographs. Nowadays, documents are increasingly issued with the use of a digital signature. The digital signature of its origin is based on the principles of cryptography. The security key seems to be complicated for the average user. The article discusses the topic of tachograph construction, in particular the schematic responsible for information encryption.

Schlüsselwörter

  • tachograph cards
  • cryptography
  • digital tachograph system
  • recording equipment
  • road transport
Open Access

Estimation of Random Friction Forces on the Microbearing Cooperating Surfaces

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 167 - 174

Zusammenfassung

Abstract

Presented paper concerns a new mathematical form of stochastic theory of hydrodynamic friction forces occurring on the real cooperating surfaces in computer micro bearing fan and computer microbearing in hard disc driver HDD. This paper presents particularly a new-review of stochastic analytical considerations realized by the authors for friction forces estimation during hydrodynamic lubrication performed on the ground of the measurements of the gap height between two roughness surfaces. After numerous experimental measurements directly follows that the random unsymmetrical increments and decrements of the gap height of computer microbearings have important influence on the load carrying capacities and finally on the friction forces and wear of cooperating surfaces. The main topic demonstrates the influence of the variations of expectancy values and standard deviation of the computer microbearing gap height on the friction forces occurring in the HDD and microbearing fan. Moreover, it is observed the evident connection between the apparent dynamic viscosity and the features of the microbearing superficial surface. Hence after abovementioned remarks follows the corollary that the influence of the microbearing gap height stochastic variations connected with the surface roughness tend moreover indirect from the apparent viscosity into the friction forces variations. The synthetic, complex elaboration of obtained results indicates finally the influence of the random roughness in micro and nano level of microbearing surfaces on the friction forces distribution. A new results contained in this paper are obtained taking into account 3D variations of dynamic viscosity of the non-Newtonian lubricant, particularly variations crosswise the film thickness and influences of surface superficial layer features on the lubricant apparent viscosity.

Schlüsselwörter

  • microbearings
  • computer fan
  • hard disc driver bearings
  • hydrodynamic lubrication
  • analytical stochastic principles
  • analytical solutions
  • apparent viscosity depended on the gap height variations
Open Access

Stability of Wheeled Armoured Personnel Carrier Firing Sideways

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 175 - 180

Zusammenfassung

Abstract

One of the most important and commonly used means of transport in the armed forces of various countries is wheeled armoured personnel carriers. After proper preparation, beside transport tasks, they can carry out special tasks, as part of regular and irregular activities within purpose of supporting actions of troops. This paper presents preliminary results of numerical research of wheeled armoured personnel carrier with 8x8-drive system. The effect of impact of large calibre cannon (120 mm) with reduced recoil force on transporter behaviour was investigated. The research object model consists of shell, solid and discrete elements. The research was carried out in the LS-DYNA software. Considered variant applies to sideways firing (to the left of the vehicle) for cannon elevation angle 16 deg. Numerical model of standing still on the flat ground wheeled armoured personnel carrier was preloaded with the gravitational force. The results of post-firing vehicle behaviour including angular displacement of the hull, dynamic deflections of the suspensions and impact on the stability of the wheeled vehicle were evaluated.

Schlüsselwörter

  • wheeled vehicle
  • vehicle dynamics
  • vehicle stability
  • armament
  • finite element method
Open Access

The Impact of a Place for the Measurement of Cylinder Pressure of Marine Piston Engine on the Indicator Diagrams and Indicator Parameters

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 181 - 188

Zusammenfassung

Abstract

The article discusses one of the most popular methods of diagnosing selected damages of marine piston engines, which is the indication or measurement of pressure changes in the engine’s combustion chamber. Improving the quality of indicator diagrams may contribute to the increase in the efficiency of using the parameters indicated in the diagnostics of marine piston engines. Measurement errors during engine indication are primarily caused by measuring channels that connect the combustion chamber to the pressure sensor. One way to avoid these errors is to install the pressure sensor directly in the combustion chamber. It seems that it is possible to eliminate these errors. However, there is a risk that the pressure sensor will be damaged by the effect of high temperature on it during combustion of the fuel-air mixture in the engine’s combustion chamber. The article presents the results of tests that indicate that the measured temperatures in the place where the sensor was installed (in the combustion chamber) did not exceed the critical value specified by the pressure sensor manufacturer. The article also presents the results of cylinder pressure measurement not only in the combustion chamber but also in two other points - on the thread of the indicator cock and in the measuring channel between the indicator cock and the cylinder head. The tests were carried out in a wide range of engine load technically efficient and with simulated damage in the fuel injection system. The article presents a comparative analysis of the parameters read out of the indicator diagram for the three above-mentioned pressure measurement locations. It was shown that the pressure measurements carried out directly in the combustion chamber are free from errors resulting from the influence of measuring channels and indicator cock.

Schlüsselwörter

  • diagnostics
  • marine piston engines
  • self-ignition engines
  • indication
  • middle indicated pressure
  • combustion pressure
Open Access

Influence of Seawater Salinity on Corrosion of Hull Structural Steel

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 189 - 195

Zusammenfassung

Abstract

Hulls of ships are often made of steel, which are produced under the supervision of classification societies. Usually, the hull steel of ordinary strength category A is used for the ship's shell (the yield strength is 235 MPa and the impact strength 27 J at 20ºC). Vessels sail in sea areas with various levels of salinity and thus with different corrosiveness. The average salinity of the seas is taken as 3.5% content of sodium chloride. This article presents the results of corrosion tests of S235 JRG1 steel in an aqueous solution in which the mass fraction of sodium chloride was: 0.7%, 1.4%, 2.2%, 2.8%, 3.5% and 4.2%. Corrosion tests were performed using the potentiodynamic method. As parameters characterizing the corrosion properties of the tested steel, the corrosion current density and corrosion potential were assumed. Statistically significant influence of seawater salinity on the corrosion properties of hull structural steel of ordinary strength of category A was found. The highest value of the corrosion current density was observed in the solution containing 3.5% NaCl mass fraction was observed. In seawater with a sodium chloride content in the range of 0.7 to 3.5%, an increase in the value of the corrosion current density was observed, along with the increasing share of NaCl. In seawater with higher salinity, the corrosion rate was reduced. The corrosion potential of S235JRG1 steel decreases with the NaCl content in the corrosive solution. The susceptibility of this material to corrosion in seawater increased.

Schlüsselwörter

  • hull structural steel
  • corrosion
  • potentiodynamic test
  • seawater
Open Access

Inverse Problem of Selection of the Theoretical Cycle for the Real Cycle of Internal Combustion Engine

Online veröffentlicht: 10 Oct 2019
Seitenbereich: 197 - 204

Zusammenfassung

Abstract

The effectiveness of work of an internal combustion engine can be assessed by means of the energy efficiency: theoretical, internal and effective... In the problem regarding the efficiency of obtaining a work from the tested SI engine, the theoretical Seiliger-Sabathe cycle was adopted as a reference model for the real engine cycle. For comparison, the OTTO cycle was also analysed. The engine indicating allows direct determination only of internal work. However, determining the work of the theoretical cycle first requires solving the problem of selecting the parameters of the theoretical cycle, according to the real cycle of the engine (inverse problem). In order uniquely to determine the course of the theoretical Seiliger-Sabathe cycle, it is necessary to determine the parameters of the starting point and the heat distribution number. The selection of the theoretical cycle for the real cycle, within the scope of determining the number of heat distribution, is to some extent of a contractual nature. Therefore, the problem of determining the number of heat distribution was solved by two own original methods. A comparison of the real cycle with the theoretical cycle determined for it is presented.

Schlüsselwörter

  • internal combustion engine
  • real cycle
  • theoretic cycle
  • heat distribution number
  • the reconciliation algorithm

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