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Volume 26 (2019): Edition 4 (December 2019)

Volume 26 (2019): Edition 3 (September 2019)

Volume 26 (2019): Edition 2 (June 2019)

Volume 26 (2019): Edition 1 (March 2019)

Volume 25 (2018): Edition 4 (December 2018)

Volume 25 (2018): Edition 3 (September 2018)

Volume 25 (2018): Edition 2 (June 2018)

Volume 25 (2018): Edition 1 (March 2018)

Volume 24 (2017): Edition 4 (December 2017)

Volume 24 (2017): Edition 3 (September 2017)

Volume 24 (2017): Edition 2 (June 2017)

Volume 24 (2017): Edition 1 (March 2017)

Détails du magazine
Format
Magazine
eISSN
2354-0133
Première publication
20 Dec 2019
Période de publication
4 fois par an
Langues
Anglais

Chercher

Volume 26 (2019): Edition 4 (December 2019)

Détails du magazine
Format
Magazine
eISSN
2354-0133
Première publication
20 Dec 2019
Période de publication
4 fois par an
Langues
Anglais

Chercher

37 Articles
Accès libre

Operational Verification of a Ship Main Power System Element Choice – Case Study

Publié en ligne: 24 Apr 2020
Pages: 7 - 14

Résumé

Abstract

The article refers to results and conclusions on post-emergency repairs of a turbo-charging system of a DEUTZ engine of the SBV 8M 628 type of 1715 kW – the main power unit of a cement carrier. The failure of the turbocharger led to severing of a part of the exhaust outlet valve head. In order to determine the cause of the turbocharger fault, parametric identification of the reference state of the turbocharging system interacting with the ship main power engine has been carried out. The post-emergency servicing of the turbocharger comprised mounting a new blade rim of expansive instruments of smaller capacity than the so far used. Control measurement results of the power system after the replacement of the turbocharger turbine nozzle have been presented. Limitations of correct engine operation have been noted in the range of maximum load with continuous power (MCR). A range of corrective maintenance servicing of fuel equipment has been presented. Using the values of measured torque at the propeller shaft, incorrect interaction between the shaft and the main engine has been noted. A new propeller, adequate to the design operational parameters of the engine characteristics, has been chosen and mounted. The correctness of turbine expansive instrument replacement has been verified by correct interaction between the elements of the power system: propeller – main engine – turbocharging system. Thus, a wider range of economically acceptable ship operation has been obtained.

Mots clés

  • a ship main power system
  • turbo-charging system
  • operational parameters
  • main engine
  • ship propeller
Accès libre

Analysis of Possibility Limiting the Time of Test Injector in Diesel Engine Using Factory Test Bench Producers of these Elements

Publié en ligne: 24 Apr 2020
Pages: 15 - 20

Résumé

Abstract

Regeneration of parts is the most correct form of use of worn out components and contributes, among others, to reduce CO2 emissions. In the case of elements of fuel injector systems, very high precision is required and such regeneration should be carried out using the original parts. It also requires testing on the original testing stands of these manufacturers, which very often characterized by the fact that it is not possible to perform a short test, which means that it is only possible to perform a time-consuming comprehensive test. An unquestionable advantage in some cases would be the possibility of preliminary verification of the correct operation of the regenerated subassembly without the need for a full time-consuming test. In the present situation, only after completing a time-consuming comprehensive test of the diagnosed element of the injection system, it is often necessary to carry out its disassembly, replacement or correction of one of the components and reassembly with the next time-consuming test. In the case of low unemployment in the labour market, this is extremely unfavourable, and it is often not possible to organize work in such a way that the diagnostic test of the subassembly takes place without the participation of an employee. On the basis of the analyses presented in this article, carried out in the research and development department in company whose employee is one of the co-authors, it can be stated that in the current situation on the labour market where skilled workers are required to work and for the development of science is the most purposeful recognition of the possibility of using vibroacoustic signals to shorten time of tests, which with a high probability may end in a negative result. The preliminary analysis carried out, show that limitation of diagnostic time can be over 35%.

Mots clés

  • transport
  • road transport
  • simulation
  • combustion engines
  • air pollution
  • environmental protection
Accès libre

Slip at Vehicle Transmission System with Hydrokinetic Converter in the Urban Test Cycle

Publié en ligne: 24 Apr 2020
Pages: 21 - 28

Résumé

Abstract

The study concentrated on slip phenomenon occurring at hydrokinetic converter in passenger car transmission system. Optimization of modern automatic transmission systems aims, on the one hand, to further increase the comfort of use, and on the other hand to improve the efficiency and reliability operation of individual components, in such a way as to ultimately result in lowering fuel consumption and also harmful emissions. One of the important factors affecting the mentioned transmissions properties as a whole system is the slip phenomenon occurring between the pump and the hydrokinetic converter turbine. The study presents the results of research on ZF 4HP20 and Fuji Hyper M6 gearboxes operating in vehicle transmission systems. The tests were carried out using the MAHA MSR 500 chassis dynamometer during driving at chosen test cycles. The research covered the transmission systems operating according to selected control algorithms affecting not only the gear shifting strategy but also the operation of the lock up clutch causing the transmissions slip values. As shown by the conducted research, the algorithm controlling the operation of the torque converter can have a significant influence on their operating indexes. The conducted analyses indicate the possibilities of improving the transmission operating indexes, especially in urban driving cycles.

Mots clés

  • hydrokinetic transmission
  • transmission slip
  • test cycle
  • chassis dynamometer
Accès libre

Simulations of the Influence of the Heat Flux at the Shaft Surface of the Conical Slide Bearing on Its Hydrodynamic Lubrication and Operating Parameters

Publié en ligne: 24 Apr 2020
Pages: 29 - 37

Résumé

Abstract

The aim of this work is to investigate, how in the adopted model of hydrodynamic lubrication of a conical slide bearing, the change of the heat flux value at the bearing shaft, affects bearing operating parameters. In this research, the authors use, the known from the literature, Reynolds type equation, describing the stationary hydrodynamic lubrication process of a conical slide bearing. The analytical, solutions, that determine the components of the lubricating oil velocity vector and the equation (analytical solution of energy equation) determining the three-dimensional temperature distribution in the lubrication gap, was also adopted from previous works. In order to obtain numerical solutions, the Newton’s method was used, and the derivatives in the Reynolds type equation were approximated by the finite differences. An application of the method of subsequent approximations allowed considering the influence of temperature, pressure and shearing rate on the viscosity of lubricating oil. The considerations were performed by adopting the Reynolds condition of the hydrodynamic oil film. It was tested, how the assumed value of the heat flux on the bearing shaft surface affects the values of the obtained operating parameters, i.e. the transverse and longitudinal component of the load carrying capacity, friction force and coefficient of friction.

Mots clés

  • hydrodynamic lubrication
  • slide bearing
  • conical bearing
  • heat conduction
  • pressure distribution
  • viscosity
Accès libre

Modelling Method of Dynamic Characteristics of Marine Thin-Walled Structure

Publié en ligne: 24 Apr 2020
Pages: 39 - 46

Résumé

Abstract

Thin-walled structures are very popular in industries, especially in the field of shipbuilding. There are many types of equipment and structures of ships, which are made up of thin-walled structures such as hull, deck and superstructure. Therefore, the analysis and understanding of the static and dynamic characteristics of a thin-walled structure are very important. In this article, we focus on vibration analysis of a typical thin-walled structure-rectangular plate, a basic structure of the hull. Vibration analysis of a rectangular thin plate is conducted by two methods: numerical modelling method of the finite element on Patran-Nastran software platform and experimental method implemented in the laboratory of Gdynia Maritime University. Thin rectangular plate is fixed one end by four clamping plates and is modelled with finite elements and different meshing densities. The numerical model of thin rectangular plate is divided into four cases. Case 1, thin rectangular plate, and clamping plates are modelled with two-dimensional elements. Case 2, the rectangular thin plate is modelled with two-dimensional elements; the clamping plates are modelled with three-dimensional elements. Case 3, both the rectangular thin plate and clamping plates are modelled with three-dimensional elements. Case 4, the rectangular thin plate, and clamping plates are modelled with three-dimensional elements with larger mesh density to increase the accuracy of the calculation results. After that, the results of vibration analysis according to the numerical modelling method on Patran-Nastran software platform for these cases were compared with the measurement results. From there, assess the accuracy of analysis results of selected numerical model methods and the ability to widely apply this numerical model method to other marine structures.

Mots clés

  • Thin-walled structure
  • Vibration
  • FEM
  • rectangular plate
  • Patran-Nastran software
Accès libre

Mechanical Properties of AW-5083 Alloy Joints Welded By Hybrid Method – FSW and MIG

Publié en ligne: 24 Apr 2020
Pages: 47 - 52

Résumé

Abstract

The article presents the research results on the mechanical properties of aluminum alloy AW-5083 and its joints welded by hybrid method – traditional MIG and FSW. AW-5083 alloy is the most currently used in shipbuilding industry. Friction Stir Welding (FSW) – a new technology can be successfully used for butt-welding of different types of aluminum alloy sheets. FSW method can be an alternative to traditional arc welding methods i.e. MIG or TIG. Hybrid welding (FSW with MIG or TIG) could be used in cases when joining only by FSW is not possible. Welding parameters used for the connection of the sheets were presented. Metallographic analysis showed the correct construction of structural bonded joints. The research was carried out using a static tensile test in accordance with the requirements of the Standard PN-EN ISO 4136:2013-05. Flat samples cut perpendicular to the direction of rolling were used. The research was conducted at the temperature of +20ºC. The test shows that the mechanical properties of joints made by hybrid method compered to native material were lower. The tensile strength of joint was lower by 20% then native material 5083 while its yield stress was lower only about 6%. The biggest change was observed in case of plastic properties. Elongation of joint was over 50% lower compared to native material. Despite the decrease of mechanical properties, they meets the requirements of classification societies, so the conclusion is that hybrid method (FSW and MIG) of joining AW-5083 can be applied in shipbuilding industry.

Mots clés

  • hybrid welding
  • Friction Stir Welding (FSW)
  • welding
  • MIG
  • aluminium alloys
  • joints
  • mechanical properties
  • shipbuilding
Accès libre

Distributions of Hydrodynamic Pressure in the Gap of Slide Journal Bearing Lubricated with Ferro-Oil

Publié en ligne: 24 Apr 2020
Pages: 53 - 61

Résumé

Abstract

This research work is part of a broader comprehensive issue, which is the analysis of flow and operating parameters of journal slide bearings lubricated with ferro-oil. In this article, the author presents only the main assumptions and essential transformations of the analytical and numerical model for determining the pressure distributions in the gap of a slide journal bearing lubricated with ferro-oil. It is cardinal that the rheological and magnetic values of ferro-oil parameters adopted in numerical calculations are based on the results of actual values obtained in the author’s earlier research work. There are presented the pressure distributions by abovementioned method in the article for cases of bearings lubricated with ferro-oils with different concentration of magnetic particles. The obtained results are shown in the form of a set of four complementary characteristics of the dimensionless pressure distributions. First and main of them are the calculations for classical Newtonian lubrication but they take into account the influence of the magnetic field on the distributions. The next of the presented characteristics are so-called “corrections” of pressure distribution values, taking into account as follows: effects of changes in ferro-oil viscosity related to temperature changes, impacts of ferro-oil viscosity changes related to pressure changes and the effect of non-oil properties of the lubricant. The article includes a qualitative and quantitative analysis of the obtained results as well as observations and conclusions are presented in it.

Mots clés

  • temperature distribution
  • journal slide bearings
  • ferro-oil
Accès libre

The Development of the World Fleet of Electric Vehicles in Years 2010–2017 with Emphasis on Fuel-Cell Vehicles

Publié en ligne: 24 Apr 2020
Pages: 63 - 68

Résumé

Abstract

The article discusses the development of the world EV fleet in years 2010-2017. Estimates of fleet of plug-in hybrid electric vehicles (PHEV) and BEV in the world are presented. The total number of PHEVs registered in the world in 2016 was roughly 800 thousand (650 thousand in EU). Despite the fact that the sale of electric vehicles has increased considerably in recent years, in particular over 1.1 million in 2017, and also hybrid electric vehicles (PHEV) to approx. 760 thousand in 2017. The article also discusses the development of the electric vehicles market and annual new registrations of vehicles in a breakdown into respective countries. China is the definite leader in this area. In 2017 there were almost twice more BEVs registered in China than in the US and EU together. While the increase in the sale of BEVs in years 2016-2017 in the EU and the US accounted for approx. 50%, it came to over 90% in China. Among eight top worldwide BEV producers, there are four Chinese manufacturers. In the analysed 2017, there were slightly more than 7 thousand of hydrogen-fuelled passenger cars (FCEV) in use, with over 3,500 in the US, 2,300 in Japan and approx. 1,200 in Europe, and several hundred hydrogen-fuelled buses and several dozen hydrogen-fuelled trucks. The article also addresses the development of hydrogen refuelling stations (HRS) in recent years in different countries in the world, bearing in mind that the quantitative development of the hydrogen-fuelled car fleet is strongly associated with the number of hydrogen refuelling stations.

Mots clés

  • passenger cars
  • electric vehicle
  • fuel cells
  • hydrogen
  • environment
Accès libre

Comparative Preliminary Unit Costs Analysis of the Operation of Passenger Cars with Combustion Engines and Fuel Cell Vehicles Powered by Hydrogen

Publié en ligne: 24 Apr 2020
Pages: 69 - 74

Résumé

Abstract

The article presents political and legal aspects regarding the recommendation for the development of hydrogen technology in the economy and in transport. The development of electric cars with hydrogen-powered fuel cells, which took place in recent years in the world, has been outlined. The principles of calculation of average vehicle operating costs applicable in the transport economics are discussed. The estimated average unit operating costs of a statistical passenger car using conventional energy carriers, estimated in the studies of the Motor Transport Institute are quoted. The assumptions and results of the estimation of the average cost per 1 vehicle-kilometre of the electric passenger car’s mileage (BEV) have been presented, as well as the assumptions and results of the estimation of the average unit operating costs of a hydrogen powered passenger car (FCEV). The average unit costs of the mileage of these vehicles have been compared. The predictions regarding the future changes in the average prices of FCEV vehicles have been cited and the average unit costs of operating electric cars with fuel cells by the 2050 have been estimated. The project of administrative support for the development of low-emission transport in Poland was indicated.

Mots clés

  • passenger cars
  • fuel cells
  • hydrogen
  • costs
Accès libre

Self-Learning Control Algorithms Used to Manage the Operating of an Internal Combustion Engine

Publié en ligne: 24 Apr 2020
Pages: 75 - 82

Résumé

Abstract

The article presents the possibility of using self-learning control algorithms to manage subassemblies of an internal combustion engine in order to reduce exhaust emissions to the natural environment. In compression ignition (CI) engines, the issue of emissions mainly concerns two components: particulate matter (PM) and nitrogen oxides (NOx). The work focuses mainly on the possibility of reducing the emission of nitrogen oxides. It is assumed that the particularly problematic points when it comes to excessive emission of harmful substances are the dynamic states in which combustion engines operate constantly. In dynamically changing operating points, it is very difficult to choose the right setting of actuators such as the exhaust gas recirculation (EGR) valve to ensure the correct operation of the unit and the minimum emission of these substances. In the light of the above, an attempt was made to develop a self-learning mathematical model, which can predict estimated emission levels of selected substance basing on current measurement signals (e.g. air, pressure, crankshaft rotational speed, etc.). The article presents the results of the estimation of nitrogen oxides by the trained neural network in comparison to the values measured with the use of a sensor installed in the exhaust system. The presented levels of estimated and measured results are very similar to each other and shifted over time in favour of neural networks, where the information about the emission level appears much earlier. On the basis of the estimated level, it shall be possible to make an appropriate decision about specific settings of recirculation system components, such as the EGR valve. It is estimated that by using the chosen control method it is possible significantly to reduce the emission of harmful substances into the natural environment while maintaining dynamic properties of the engine.

Mots clés

  • transport
  • simulation
  • combustion engines
  • environmental protection
  • neural network
Accès libre

Validation of Microscopy Measured Porosity in Carbon Fibbers Composites

Publié en ligne: 24 Apr 2020
Pages: 83 - 90

Résumé

Abstract

One of the most common defects in carbon fibre reinforced plastics (CFRP) is porosity. Too much of those defects could be serious problems to mechanical properties, which directly take effect on elements safety, like aircrafts. Therefore, the evaluation of porosity is very important test. Microscopic observations are widely used as a quality instrument in materials and constructions inspections. Cross section image of a material is easy to prepare and analyse. Porosity of a carbon fibre reinforced plastic can be clearly spot in such kind of images. Study shows that in the most cases porosity appear between layers of fibres, rather between fibres. Unfortunately, image from microscope is only 2D picture from a small representative region. Because of that, comparison of 2D image to a real porosity distribution in all volume of a material is very difficult. To verify 2D microscopic observation method is necessary to perform another kind of tests. In this article, authors focused on non-destructive (NDT) and destructive testing methods. 2D porosity images from light microscope were compared with three different testing methods: ultrasonic test (UT), computed tomography (CT) test and constituent content of composite materials standard test method according to ASTM D3171 – 15, procedure B. Porosity results obtained from dissolution of resin from the carbon-epoxy resin sample.

Mots clés

  • porosity
  • carbon fibre
  • microscope
  • UT (Ultrasonic test)
  • CT (computed tomography)
Accès libre

Energy Balance of a Vehicle Equipped with Hybrid Propulsion System Fuelled with Alternative Fuels

Publié en ligne: 24 Apr 2020
Pages: 91 - 96

Résumé

Abstract

Article presents the energetic balance of small-unmanned vehicle hybrid power transmission. The vehicle equipped with serial hybrid transmission consisted of electric engines connected to the battery pack and small Diesel power generator. In mentioned construction, battery is used as energy buffer and combustion engine is used more as emergency power supply, and is turned on when battery is depleted. In other condition, power generator can be turned off, without reducing power of transmission parameters, except its range. Vehicles with hybrid drive are very common chosen vehicles by users. More and more often, we also talk about searching for replacement fuels for internal combustion engines, so also for those with hybrid drive. The research was carried out on an unmanned land platform equipped with a hybrid propulsion system supplied as standard with Diesel oil. The article presents the problems of comparing the efficiency of a hybrid vehicle fuelled with Diesel oil, but also with alternative fuels based on kerosene and other components. For test, three types of fuels were used, standard Diesel oil, F-34 and with experimental mixture of Jet A-1 fuel with 10% of 2-ethylhexanol. Energy used for charging of the battery, from tank-to-wheel, was calculated. This also enables to calculate total efficiency of such hybrid power transmission, powered with different fuels.

Mots clés

  • energy balance
  • unmanned vehicle
  • hybrid transmission
  • test stand
Accès libre

Analysis of Electric Vehicles Efficiency and their Influence on Environmental Pollution

Publié en ligne: 24 Apr 2020
Pages: 97 - 104

Résumé

Abstract

Electric vehicles are increasingly present on the roads of the whole world. They have the opinion of ecological vehicles, not polluting the environment. Society is more and more often persuaded to buy electric cars as an environmentally friendly solution but is this for sure? Electric cars need quite a lot of electricity accumulated in batteries to drive on a long range. During the charging process, this energy is obtained from the electricity network, to where it is supplied by power plant. Electricity production from renewable sources is a privilege for the rare. However, electric cars are charged from the electricity grid, which in large part energy comes from non-renewable fuels. The efficiency of energy production in power plants and the energy transmission and conversion chain causes that only part of the energy produced in this way goes to the vehicle’s wheels. Although the power plants are equipped with more and more efficient exhaust gas cleaning systems, they do not clean them up to 100%. Sulphur, nitrogen, mercury and heavy metals remain in the exhaust. The article is an attempt to answer the question whether the total emission of toxic components associated with the use of an electric vehicle is not bigger than in a traditional internal combustion engine.

Mots clés

  • electric vehicle
  • exhaust gas toxic components
  • electro power plants
  • electricity production
Accès libre

Determination of Material Characteristics Necessary for Modelling of Marine Structures Exposed to Small-Calibre Bullet

Publié en ligne: 24 Apr 2020
Pages: 105 - 111

Résumé

Abstract

The article presents the results of tests of impact properties of steel 1.3964 used on the construction of modern mine destroyers. Ships of this type, like any other military unit, may be exposed to small-calibre projectiles. Firing can be done, for example, from aircraft, drones or pirate units. The thickness of the plates used in the ship’s construction does not guarantee effective resistance to the projectile calibre 7.62 mm for all compartments of such ships. Thus, it is possible to modify the existing structure or apply additional solutions that will ensure a certain level of ballistic resistance. Solutions of this type are necessary in order to maintain the stability and buoyancy of the ship at the current level. During the tests, a stress-strain curve for steel 1.3964 was obtained, then the Johnson-Cook plasticity and damage model was proposed, which was used in the FEM simulation. The task was modelled as non-linear considering the deformation of both the sample and the projectile. The simulation was prepared in the CAE program, and then verified by an experiment on the shooting range. The results were presented in the form of diagrams and deformation figures, and were compared with photographs of samples and velocities after the specimen.

Mots clés

  • sea constructions
  • CAE
  • marine mine destroyer
Accès libre

Using Sorbents for Oil Spill Clean-Up in Ports and Coastal Areas

Publié en ligne: 24 Apr 2020
Pages: 113 - 117

Résumé

Abstract

Petroleum substances are a mixture of many hydrocarbons of various structures; some of them are toxic for marine organisms. In case of pollution of the aquatic environment, these compounds may enter seawater organisms and adversely affect gas exchange and inhibit photosynthesis. Therefore, it is important to take measures to reduce the emissions of these compounds into the aquatic environment and quickly to remove possible spills of uncontrolled pollution. Sorbents are materials that soak up oil from water. They are best suited for the absorption of oil – derived substances. They are used to absorb leaks in open and closed tanks, particularly in hard – to-reach places. Sorbents can be natural organic, natural inorganic or synthetic. Natural sorbents are divided to organic materials such as peat moss or wood products, and inorganic materials such as vermiculite or clay. Sorbents are available in a loose form, which includes granules, powder, chunks and cubes. Synthetic sorbents are used to wipe other oil spill recovery equipment such as skimmers and booms after a spill clean-up operation. The thesis deals with the issues related to the analysis of the possibility of using sorbents to combat oil pollution in port and coastal areas. The article discusses the types of pollution occurring in coastal waters, as well as the types of sorbents used and the forces and measures to combat pollution. The characteristic features of sorbents are rate of absorption and adsorption, oil retention and ease of application. Absorption tests were carried out and the best sorbents for combating oil pollution were selected.

Mots clés

  • materials engineering
  • maritime engineering
  • fuel
  • oils & lubrication
Accès libre

Influence of Inlet Geometry on the Efficiency of 1 MW Steam Turbine

Publié en ligne: 24 Apr 2020
Pages: 119 - 126

Résumé

Abstract

The process of the design of the 1 MW steam turbine includes designing the stator and rotor blades, the steam turbine inlet and exit, the casing and the rotor. A turbine that operates at rotation speeds other than 3000 rpm requires a gearbox and generator with complex electronic software. This article analyses the efficiency of eight turbine variants, including seven inlet geometries and three stages of stator as well as an eight variant with one of the inlets, all three stages and an outlet.

This article analyses the efficiency of 8 turbine variants, including four spiral inlet geometries and tree stages in a 1 MW steam turbine. In the article, inlets and 1st stator blades of various geometries were analysed to obtain maximal turbine efficiency. Changing the inlet spiral from one pipe to two pipes increased the turbine efficiency. The geometry of the blades and turbine inlets and outlet was carried out using Design Modeller. The blade mesh was prepared in TurboGrid and inlet in ANSYS Meshing.

Mots clés

  • turbine engine
  • steam turbine
  • turbine inlet
Accès libre

Technical and Ecological Analysis of Different Solutions of the Power Supply of a Marine Diesel Engine

Publié en ligne: 24 Apr 2020
Pages: 127 - 134

Résumé

Abstract

The article contains provisions on the prevention of sea pollution by ships, including, inter alia, the International Convention for the Prevention of Pollution from Ships, developed in 1973 (MARPOL). The convention aims to protect the marine environment from oil and its derivatives. Special areas, where extraordinary measures have been taken to prevent sea pollution, due to the intensity of ship traffic and the greater threat of damage to the marine environment have also been presented. In the further part of the article, the applicability of various pro-ecological solutions, i.e. the use of catalysts, low-sulphur fuels, and in the case of using residual fuels – exhaust gas scrubbers were described. In the main part of the article, a technical and ecological analysis was made. In addition, difficulties resulting from the use of pro-ecological solutions were described. The costs of using low-sulphur fuel meeting the emission standards, installing the scrubber and modification of the natural gas combustion unit were compared with the assumption of ten years of passenger-car ferry sailing. Then the problems that individual solutions create were shown. In the final part of the article, alternatives to those described, i.e. the liquefied natural gas (LNG) power supply, electric and hydrogen drives were presented.

Mots clés

  • technical analysis
  • special areas
  • exhaust gas scrubbers
  • alternative drives
Accès libre

Composite Materials for Warship Constructions

Publié en ligne: 24 Apr 2020
Pages: 135 - 140

Résumé

Abstract

The article presents the basic properties of composite materials used for the construction of special ships. Static and dynamic characteristics of materials such as wood and polyester-glass composites are presented. Noteworthy are materials such as surface modified wood and polyester-glass composites with the addition of recyclate. Composite materials are widely used materials for the construction of non-magnetic warships. The article describes the properties of surface modified wood with polymethyl methacrylate and a polyester-glass composite with the addition of recyclate. The recyclate is fragmented, milled polyester-glass scrap. The content of the recyclate greatly affects the mechanical properties of the composite. The properties of the composite with the addition of recyclate depend on the recyclate content as well as the production technology and size of the recycled granulates. The test results showed that the increase in the recycled content causes a decrease in the mechanical properties of the composite. However, it should be remembered that these materials originated from waste, waste that is not subject to self-degradation, which have a very negative impact on the natural environment. At present, where there is a very large pollution of the natural environment, the processing and management of huge amounts of composite waste is an essential goal. A significant amount of recyclate significantly reduces the mechanical properties of the composite; however, the same large amount of recycled material has been transformed and used. The manufactured material and its structural elements are still non-magnetic structures and can be used on a less loaded element. The choice of material for the construction of special ships elements is determined not only by its properties but also by knowledge, experience, method of processing, economic and technical risk.

Mots clés

  • polyester-glass composites
  • recyclate
  • modified wood
  • non-magnetic warships isotropic
Accès libre

The Influence of Cutting Parameters on Surface Topography During Turning Marine Pump Shafts

Publié en ligne: 24 Apr 2020
Pages: 141 - 148

Résumé

Abstract

One of the greatest problems of modern production techniques is the achievement of an appropriate quality at minimal costs and accompanied by the production efficiency increase. Therefore, while designing the production process. The technology used should have a considerable influence on the durability and reliability of machine parts to be produced. During finish treatment, the final dimensions as well as functional properties are imparted to a given element by application of proper treatment type. The engineer has a range of production techniques to choose for the proper surface layer formation. Conventional turning machines belong to the basic equipment of ships, because in sea conditions, they enable the execution of a spare part or carrying out the necessary operations in the process of their regeneration. The use of modern cutting tools makes it possible to obtain a surface with low values of surface roughness parameters. The use of new generation cutting inserts on conventional lathes can cause problems for operators. The lack of the ability to ensure proper of treatment condition and setting errors of cutting tools contribute to the damage of the cutting insert or the surface of the workpiece. The article presents the results of influence of different cutting parameters on surface topography during turning process of stainless steel. A shaft made of 304L stainless steel was used for the research. The cutting process was carried out on a universal TUM 25B x 500 centre lathes. During the turning the following machining parameters were used: cutting speed Vc [m/min], feed f [mm/rev] and depth of cut ap [mm].The turning process was conducted by a cutting tool with CCGT 09T302 UM, CCGT 09T304 UM and CCGT 09T308 UM inserts. Measurement of surface topography was carried out by T8000 profilometer.

Mots clés

  • finish turning process
  • surface topography
  • cutting parameters
  • stainless steel
Accès libre

Comparative Analysis of Fuels Derived from PE Plastic Waste with a Mixture of Plastic Recycling Waste of Codes: 1, 2, 4, 5, 6 and 7 Based on Low-Temperature Pyrolysis

Publié en ligne: 24 Apr 2020
Pages: 149 - 154

Résumé

Abstract

Thanks to their numerous advantages, plastics are becoming more and more widely used in all branches of industry. The quantities of products, their packaging and, consequently, the amount of synthetic polymer waste are steadily increasing, what poses a high risk to the environment due to their long decomposition time. To reduce waste production is practically impossible, therefore it is very important to constantly implement new and improve existing methods of waste treatment. The following article presents one of the alternative methods for synthetic polymer waste treatment, which is low-temperature pyrolysis. Two pyrolysis processes were carried out. During the first experiment a polyethylene plastic material was used, in the second experiment a mixture of typical household recycling waste of codes 1, 2, 4, 5, 6, and 7 were tested. During the thermal processing, the input material undergoes a chemical transformation due to breaking of long hydrocarbon chains. At the same time, high-energy density products, such as petroleum products and gas, are produced. The main advantage of the presented method is that it allows reducing preliminary technological processes to a minimum and it is easily automated, as it reduces the process to one compact installation. The reduction of the amount of stored waste and the recovery of petroleum derivatives, are additional advantages of pyrolysis implementation. That, in consequence allows reducing consumption of fossil fuel resources.

Mots clés

  • pyrolysis
  • plastics
  • waste
Accès libre

Application of Similarity Method of Distance Courses Describing the Elements Content in Cement Concrete After 50 Forced Thermal Cycles

Publié en ligne: 24 Apr 2020
Pages: 155 - 162

Résumé

Abstract

The article presents material solution based on the application of ceramic dust as concrete mix component intended for airfield pavements. The applied dust influences the changes in internal structure of concrete composite. Diversification of internal microstructure of cement concrete using the suggested dust has significant influence on the improvement of compressive strength. The laboratory analyses included concretes curing in standard conditions and concretes subject to thermal cycles representing the destructive influence of imposed loading. Comparative SEM observations of concretes subject to 50 thermal cycles proved significant influence of dust on internal structure of composite. In the study 6 samples were selected, which, each time, were intended for the laboratory tests. The applied similarity analysis of distance courses in case of this concrete. Similarity indexes between input and target sequence were defined. Diagrams presenting the similarity of the analysed concretes were prepared (after 28 days of curing and after 50 thermal cycles). It was proved that the suggested method can be used to assess the elements content and define the similarity of concrete intended for airfield pavements in the selected of areas (cement matrix, contact area between fine aggregate and cement matrix, contact area between coarse aggregate and cement matrix and contact area between air voids and cement matrix).

Mots clés

  • cement concrete
  • airfield pavement
  • analysis of similarity
  • forced thermal cycles
Accès libre

Application of Similarity Method of Distance Courses Describing the Elements Content in Typical Cement Concrete After Thermal Cycles

Publié en ligne: 24 Apr 2020
Pages: 163 - 170

Résumé

Abstract

The work concerns the use of similarity analysis of distance course. Composition of concrete mixes was designed. The cement concrete composition includes cement, coarse aggregate, fine aggregate, water and admixtures. The laboratory analyses included concretes curing in standard conditions and concretes subject to thermal cycles representing the destructive influence of imposed loading. Laboratory tests assumed the fifty thermal test cycles. A single test cycle included process of alternate heating and cooling. Recurrent influence of temperature stimulated the impact of aircraft on airfield pavements. The assumed heating and cooling time corresponded to the time during which the aircraft effected the most frequently used airfield pavement within the area of Poland. Comparative SEM observations of concretes subject to thermal cycles were conducted. An increase in the width of microcracs has been observed. In case of crystallization, there is diversification within the area of cement matrix, contact area between cement matrix and aggregate grains and in case of porosity characteristics of both concretes. Similarity indexes between input and target sequence were defined. Diagrams presenting the similarity of the analysed concretes were prepared (after 28 days of curing and after thermal cycles). It was proved that the suggested method could be used to define the similarity of concrete intended for airfield pavements.

Mots clés

  • cement concrete
  • airfield pavement
  • analysis of similarity
  • thermal cycles
Accès libre

Operating Parameters of a Slide Bearing with Parabolic-Shaped Slide Surfaces with Consideration of the Stochastic Changes in the Lubrication Gap Height

Publié en ligne: 24 Apr 2020
Pages: 171 - 178

Résumé

Abstract

In this article, the authors present the equations of the hydrodynamic theory for a slide bearing with parabolic-shaped slide surfaces. The lubricating oil is characterized by non-Newtonian properties, i.e. an oil for which, apart from the classic oil viscosity dependence on pressure and temperature, also an effect of the shear rate is taken into account. The first order constitutive equation was adopted for considerations, where the apparent viscosity was described by the Cross equation. The analytical solution uses stochastic equations of the momentum conservation law, the stream continuity and the energy conservation law. The solution takes into account the expected values of the hydrodynamic pressure EX[p(ϕ,ζ)], of the temperature EX[T(ϕ,y,ζ)], of the velocity value of lubricating oil EX[vi(ϕ,y,ζ)], of the viscosity of lubricating oil EX[ηT(ϕ,y,ζ)] and of the lubrication gap height EX[εT(ϕ,ζ)]. It was assumed, that the oil is incompressible and the changes in its density and thermal conductivity were omitted. A flow of lubricating oil was laminar and non-isothermal. The research concerned the parabolic slide bearing of finite length, with a smooth sleeve surface, with a full wrap angle. The aim of this work is to derive the stochastic equations, that allow to determine the temperature distribution, hydrodynamic pressure distribution, velocity vector components, load carrying capacity, friction force and friction coefficient, in the parabolic sliding bearing, lubricated with non-Newton (Cross) oil, including the stochastic changes in the lubrication gap height. The paper presents the results of analytical and numerical calculation of flow and operating parameters in parabolic sliding bearings, taking into account the stochastic height of the lubrication gap. Numerical calculations were performed using the method of successive approximations and finite differences, with own calculation procedures and the Mathcad 15 software.

Mots clés

  • hydrodynamic lubrication
  • analytical stochastic principles and solutions
  • apparent viscosity
  • numerical calculation
  • load carrying capacity
  • friction force
Accès libre

The Experimental Investigation of Surface Roughness After Dry Turning of Steel S235

Publié en ligne: 24 Apr 2020
Pages: 179 - 184

Résumé

Abstract

Nowadays lot of scientific work inspired by industry companies was done with the aim to avoid the use of cutting fluids in machining operations. The reasons were ecological and human health problems caused by the cutting fluid. The most logical solution, which can be taken to eliminate all of the problems associated with the use of cooling lubricant, is dry machining. In most cases, however, a machining operation without lubricant finds acceptance only when it is possible to guarantee that the part quality and machining times achieved in wet machining are equalled or surpassed. Surface finish has become an important indicator of quality and precision in manufacturing processes and it is considered as one of the most important parameter in industry. Today the quality of surface finish is a significant requirement for many workpieces. Thus, the choice of optimized cutting parameters is very important for controlling the required surface quality. In the present study, the influence of different machining parameters on surface roughness has been analysed. Experiments were conducted for turning, as it is the most frequently used machining process in machine industry. All these parameters have been studied in terms of depth of cut (ap), feed rate (f) and cutting speed (vc). As workpiece, material steel S235 has been selected. This work presents results of research done during turning realised on conventional lathe CDS 6250 BX-1000 with severe parameters. These demonstrate the necessity of further, more detailed research on turning process results.

Mots clés

  • dry turning
  • turning parameters
  • turning results
  • surface roughness
  • arithmetic average surface roughness value
Accès libre

Solutions in the Vehicle Suspension

Publié en ligne: 24 Apr 2020
Pages: 185 - 196

Résumé

Abstract

The paper presents a review of the suspension solutions used on the street vehicle up to the now a days, finalising with presentation of their damping characteristics and with evaluation of their advantages or disadvantages. Long time the suspension systems have been dominated by the classic passive suspensions realized with metallic springs, shock absorbers with constant damping coefficients and anti-roll bars, excepting some luxury and sport cars using semi-active and active suspensions. There are presented some semi-active suspension solutions with continuous or discontinuous damping characteristics adjustment and the evolution of the Citroen and other active suspensions. All of them improve in some matter the performances but all of them have not ability to recuperate energy and has auxiliary energy consumption so last period the electromagnetically shock absorbers are researched, the paper presenting some of them. The paper also presents magneto rheological MR damper, solutions for adjustable passive shock absorbers and solutions for passive shock absorbers with variable damping coefficient with the stroke, e.g. Monroe Sensa Trac, Citroën Solution and VZN solution, with their damping characteristics and performances.

Mots clés

  • active suspension
  • semi-active suspension
  • comfort
  • stability
  • clearance
  • progressive cushions
  • VZN
Accès libre

Effect of the Recyclate on a Deflection of Composites in Bending

Publié en ligne: 24 Apr 2020
Pages: 197 - 203

Résumé

Abstract

The aim of the research was to determine the effect of polyester-glass recyclate on the deflection of composite samples subjected to three-point bending. The polyester-glass recyclate was obtained from the part of the ship’s hull made of polyester-glass composite, constituting scrap metal. The pieces of scrap were pre-fragmented and then processed into a prepared stand for this purpose. Such a fragmented recycling will be used to make composites with different scrap / recycled content. For this purpose, research materials were made using the vacuum bag method with the percentage of 0%, 10% and 20% recyclate) as well as various granulation (i.e. 1.2 mm and 3.0 mm). The research material consisted of rectangular plates with a thickness corresponding to the thickness of the samples. The samples for testing were made by water cutting. The tests were carried out on a suitably prepared stand, which was made of a universal Zwick Roell testing machine and three-point bending handles and a dial indicator. The spacing of the supports has been determined in accordance with the binding standard for three-point bending. Obtained results from tests, i.e. strain, stress, deflection, deformation allowed analysing the impact of recyclate on bending strength and defining the deflection arrow. Based on the results obtained from three-point bending, it can be concluded that the polyester-glass recycling has an influence on the decrease of strength, stress and deflections of the tested composites.

Mots clés

  • recycling
  • three-point bending
  • composites
  • new materials
  • force-strain curves
Accès libre

Numerical Investigation of Endplates Influence on the Wing in Ground Effect Lift Force

Publié en ligne: 24 Apr 2020
Pages: 205 - 210

Résumé

Abstract

The article presents a comparison of the wing in ground effect magnitude of conceptual WIG craft model main characteristics for a wing with and without endplates which are also known as winglets in regular aircraft. In article, the author describes WIG effect with and WIG craft, which operates on low altitude, smaller than the length of wing chord, mostly above the water reservoir. WIG effect phenomenon is simple. The first aircraft needs to fly at adequate altitude, with a smaller distance between lower airfoil surface and ground static pressure rises, leading to rising of lift force. The main advantage of the wing in ground effect craft on regular aircraft is a much higher lift to drag ratio, also this phenomenon provides to drop in specific fuel consumption of aircraft and allows flying with heavier cargo due to higher lift force. Characteristics present in the article were designated from simulations, which were conducted in Ansys Fluent software. Results obtained for a wing with endplate in numerical analysis shows the superiority of this approach. Endplates provide to increase WIG effect by a decrease in induced drag through the move out vertices from the wing tips, which are made by differential pressure above and under the wing. As winglets in regular aircraft, endplates provide to save fuel. WIG craft does not need airports so it could be a cheap alternative for modern aircraft.

Mots clés

  • endplates
  • ekranoplan
  • numerical analysis
  • wing in ground effect
  • airfoil
Accès libre

Investigation of Thermal Properties of Novel Phase Change Material Mixtures (Octadecane-Diamond) with Laser Flash Analysis

Publié en ligne: 24 Apr 2020
Pages: 211 - 218

Résumé

Abstract

Phase change materials (PCMs) are widely used in numerous engineering fields because of their good heat storage properties and high latent heat of fusion. However, a big group of them has low thermal conductivity and diffusivity, which poses a problem when it comes to effective and relatively fast heat transfer and accumulation. Therefore, their use is limited to systems that do not need to be heated or cooled rapidly. That is why they are used as thermal energy storage systems in both large scale in power plants and smaller scale in residential facilities. Although, if PCMs are meant to play an important role in electronics cooling, heat dissipation, or temperature stabilization in places where the access to cooling water is limited, such as electric automotive industry or hybrid aviation, a number of modifications and improvements needs to be introduced. Investigation whether additional materials of better thermal properties will affect the thermal properties of PCM is therefore of a big interest. An example of such material is diamond powder, which is a popular additive used in abradants. Its thermal diffusivity and conductivity is significantly higher than for a pure PCM. The article presents the results of an analysis of the effect of diamond powder on thermal conductivity and diffusivity of phase change materials in the case of octadecane.

Mots clés

  • phase change materials
  • PCM
  • diamond powder
  • thermal conductivity
  • thermal diffusivity
Accès libre

Analysis of the Vehicle Exploitation Process with Regard to Profiling

Publié en ligne: 24 Apr 2020
Pages: 219 - 225

Résumé

Abstract

Transport telematics systems integrate information technology with telecommunications for their use in various transport systems. Thanks to the use of advanced technical solutions and modern telecommunications and IT systems, it is possible to implement additional innovative services. They can be used to rationalize the process of using and maintaining means of transport. Modern vehicles are equipped with telematic on-board systems. Such solutions combine various electronic devices used in the vehicle. For this purpose, bus solutions are used, thanks to which it is possible to control individual systems and devices. It is also possible to use the transmitted data to detect negative exploitation phenomena during vehicle use (e.g. glazing phenomenon, work in the upper engine rev range with too low coolant temperature, intensive work compressor of the high air pressure system being a symptom of inability of pneumatic systems). This is possible because the data being sent has a specific information resource. Thanks to this, to can be concluded about the loss of the exploitation potential of the vehicle. This approach will be used to rationalize the technical service of the vehicle fleet, with regard to profiling. Using exploitation data, received via a telematic interface from vehicles, it is possible to profile the rolling stock. It consists in distinguishing individual sets of vehicles due to certain reliability and exploitation properties. This approach allows for the specification of the rolling stock exploitation, giving the opportunity to rationalize the use and exploitation. The publication presents the author’s graph of the exploitation process taking into account the profiling of the vehicle fleet. The application of the presented approach will contribute to the improvement of the value of certain vehicle reliability and exploitation indicators.

Mots clés

  • transport telematics systems
  • exploitation
  • reliability
Accès libre

Modelling of Transport System Operational Reliability a Markov Approach

Publié en ligne: 24 Apr 2020
Pages: 228 - 234

Résumé

Abstract

The workability of a transport system is associated with performance and operational reliability. Operational reliability provides a measure of the probability that a transport system will realize transport process as intended. Performance reliability is an adequacy measure of transport process realization under specific environmental and traffic conditions. Transport system can be modelled as repairable, multistate, non-homogenous rectangular or dendrite system. This article provides the Markov and semi Markov models for estimation of the operational and performance reliability of city transport system. The system is semi homogenous it means that serial subsystems have the same reliability function. The reliability of any serial subsystem is exponential. The distribution of the repair time is any probability distribution. In case where the probability distribution of the repair time is exponential, the Markov process is used to construct simulation model. The simulation model was applied at Microsoft Excel. Many stochastic models in engineering, logistic and even finance or insurance are setup in a spreadsheet for simulation. The semi Markov model of the multistate reliability of repaired system is applied to the street system. The embedded Markov chain was used to count stationary probabilities. The possibility of application of the results is illustrated by an example for the systems with rectangular or dendrite shaped accordingly, consist of three types of elements.

Mots clés

  • transport
  • road transport
  • simulation
  • Markov model
  • semi Markov model
Accès libre

Anomaly of Rotor Dynamics in Ultra-Light Helicopter – Robinson R22

Publié en ligne: 24 Apr 2020
Pages: 235 - 239

Résumé

Abstract

The article presents the analysis of anomaly of rotor dynamics in ultra-light helicopter - Robinson R22. Robinson R22 is two-seat, two-blade main rotor and single-engine helicopter, well known as simple and common used aircraft because of low price and high availability. At the same time, large number of accidents and strictly defined rules (recommended piloting technique) and weather condition for safe flight show disadvantages of Robinson R22. The reason for considering this topic is the analysis of different flight properties and helicopter behaviour as well as easy entering into dangerous flight manoeuvre. In the article different flight properties and loss of control during the pull-up, manoeuvre or vertical gusts of wind and mast bumping accidents were analysed. Analysis shows that problem may be caused by construction of three-hinged rotor hub, designed and patented by F. Robinson. Article presents model of rotor hub and review of main rotor and rotor hub construction in light helicopters. Because of number of accidents, caused by the unusual behaviour of Robinson R22, restrictive pilotage rules were introduced: prohibition of flight in certain weather conditions, the necessity of attending additional training conducted by trained instructors. To reduce the probability of an accident a special instruction for specific Robinson R22 properties was created. Moreover, the statistics of accidents resulting from loss of control and review of legal changes caused by Robinson R22 accidents are presented.

Mots clés

  • rotor hub
  • Robinson R22
  • helicopter
  • the pull-up manoeuvre
  • rotor dynamics
Accès libre

Introduction to the Examination of Thin-Walled Structures Using the Vibrodiagnostic Method

Publié en ligne: 24 Apr 2020
Pages: 242 - 248

Résumé

Abstract

The article presents a methodology of non-destructive diagnostic vibratory tests of welded plates with geometrical parameters that classify them into a group of thin-walled panels. On the basis of such plates, most ship constructions are created. In previous works, the authors dealt with the study of welded joints in plates with significant thicknesses and developed for them a number of methods for assessing the quality of welded joints. Vibrodiagnostics is a NDT method that allows the use of a variety of techniques and tools. It enables measurements to be made in both a contact and non-contact way depending on the requirements of the structure and the environment. Vibrodiagnostic method is one of the most modern NDT methods, which uses modern measurement tools and computer analysis of data. On the basis of the developed methods, the authors intend to verify their application to plates from real welded constructions, which will be performed in typical shipyard conditions by welders. Such tests are important due to their use for the construction of a real SHM ship construction monitoring system. These methods allow for the examination of the condition of ships’ structural plates and can detect defects in welded joints that prevent ships from operating under severe sea conditions. The article presents the laboratory stand, the sensor layout, results, and their initial analysis.

Mots clés

  • welding
  • welded joints
  • non-destructive testing
  • vibrations
  • time – frequency characteristics
Accès libre

Numerical Investigations of Stress Concentration in Reinforcement Steel Structure by Composite Overlays

Publié en ligne: 24 Apr 2020
Pages: 249 - 256

Résumé

Abstract

The stress concentration observed in the vicinity of cut-outs and holes in structural elements significantly influences the fatigue endurance of machines subjected to cyclic loads. Numerous studies have been made so far to improve this situation and increase the structure lifetime. Several design recommendations have also been worked out to avoid the problem of premature failure. The proposed article illustrates the influence of the composite overlays applied around the cut-outs made in flat steel constructional elements subjected to axial tension. The detailed study concerns the reinforcement made from the FRP (fibre reinforcement polymer) composite applied around the notches. Two types of composite materials were used, namely: TVR 380 M12/R-glass (glass fibres embedded in epoxy resin matrix) and AS4D/9310 (carbon fibres embedded in epoxy resin matrix). In the first step, the detailed numerical studies (finite element analysis) were performed for the steel samples (with no overlays added) with cut-outs made in the form of circle, square and triangle hole (the last two with rounded corners). The results of these studies were compared with the existing analytical solutions with respect to the stress concentration factors (SCF) estimation. The relatively good conformity was observed when using dense meshes of finite elements placed around the void vicinity. In the next step, the composite overlays were applied around cut-outs and their influence on the stress concentration was investigated. The influence of the fibre orientation, numbers of layers, sizes of the composite overlay used were considered. It was proved that the application of composite overlays evidently decreases the stress concentration around the notches.

Mots clés

  • plate
  • hole
  • cut-out
  • stress concentration
  • FRP composite
  • reinforcement
  • FEM
Accès libre

Storage of Wind Power Energy

Publié en ligne: 24 Apr 2020
Pages: 257 - 264

Résumé

Abstract

There has been a big increase in production and investments in wind turbines and wind farms in last 20 years. New generation of wind turbines is more reliable than from 1980’s are, which necessary condition is energy production is to play an important role among renewable energy sources. Over the last 30 years, the size of wind turbines increased 7 times, as nominal power increased nearly 14 times. At present, turbines capable of producing over 10 MW of power are being developed. The main reason for continued growth of turbines sizes is to minimize the energy cost per kilowatt-hour. However, it is worth remembering that according to the „square-cube law”, there is a maximum size after the surpassing of witch the cost of ever-larger turbines would grow faster than financial gain from the increased size. In this article, authors present energy storage methods and devices for wind power plants and cost-effectiveness of the individual energy storage methods. Authors also present data about energy storage efficiency and groups of energy storage devices for wind power plants such as: compressed-air power stations + gas turbine (CAES), utilizing underground wells, pumped storage power plants, rechargeable batteries (lithium-ion, lead-acid, sodium sulphur, VRB, zinc-flow, zinc-air, zinc-air), flywheels, hydrogen production and storage systems, superconducting magnetic energy storage (SMES), electrostatic storage – electrolytic capacitors.

Mots clés

  • energy storage
  • wind energy
  • renewable energy
  • energy storage methods
Accès libre

Analysis of Possibility of Repairing Welding of Selected of the Steam Turbines

Publié en ligne: 24 Apr 2020
Pages: 265 - 271

Résumé

Abstract

The article presents the results of the study on the possibilities of repair by welding methods of exploitation steam turbine bodies. Two hull were investigation after a lifetime of more than 200.000 hours. Repair welding study were carried out on the L17HMF cast steel body in the immediately after exploitation condition, whereas the L21HMF cast steel body underwent a revitalization after the exploitation, and then the welding repair research were performed. On the material taken from the L17HMF cast steel hull, welding repairs were made by welding the previously cut four grooves measuring 200 mm 50 mm 50 mm, which were simulations of material defected. All samples were made in areas where maximum steam temperatures were operating. Welds were tested with destructive and non-destructive methods to determine their quality and define non-compliances detected. The L21HMF cast steel was subjected to a revitalization process, which consisted the hull in subjecting heat treatment in order to obtain favourable structural changes and improve the strength properties. Non-destructive examinations and hardness tests were carried out on the remedial weld, indicating the required quality of repairing remedial weld. Comparative study is aimed at demonstrating the main welding problems during the repair welding of exploitation steam turbine hulls.

Mots clés

  • regenerative heat treatment
  • welding
  • steam turbine
Accès libre

Modelling of Helicopter Main Rotor Aerodynamic Loads in Manoeuvres

Publié en ligne: 24 Apr 2020
Pages: 273 - 284

Résumé

Abstract

The article discusses the method of modelling of the helicopter main rotor aerodynamic loads during steady state flight and manoeuvres. The ability to determine these loads was created by taking into account the motion of each blade relative to the hinges and was a result of the applied method of aerodynamic loads calculating. The first part of the work discusses the basic relationships that were used to build the mathematical model of helicopter flight. The focus was also on the method of calculating of the aerodynamic forces generated by the rotor blades. The results of simulations dedicated to the “jump to hover” manoeuvre were discussed, showing the possibilities of analysing aerodynamic loads occurring in unsteady flights. The main rotor is considered separately in an “autonomous” way and treated as a source of averaged forces and moments transferred to the hub. The motion of individual blades is neglected, and their aerodynamic characteristics are radically simplified. The motion of individual blades is neglected, and their aerodynamic characteristics are radically simplified. This can lead to significant errors when attempting to model dynamic helicopter manoeuvres. The more complex model of helicopter dynamics is discussed.

Mots clés

  • helicopter
  • main rotor
  • aerodynamic loads
Accès libre

An Influence of Correction of the Ignition Advance Angle on the Combustion Process in SI Engine Fuelled by LPG with the Addition of DME

Publié en ligne: 24 Apr 2020
Pages: 285 - 292

Résumé

Abstract

The paper presents the results of tests of the SI engine fuelled by LPG with the addition of DME in the form of a mixture of gaseous fuels. Experimental tests were carried out on a chassis dynamometer in the full range of engine loads, at a fixed rotational speed: 2000, 2500 and 3000 rpm. The use of dimethyl ether (DME) as a fuel component makes it possible to exploit its important advantages. DME can be produced as a renewable fuel, which is important from the point of view of ecology. Another important fact is the presence of oxygen in this fuel, which has a positive effect on the engine volumetric efficiency. During the tests, the ignition timing was also adjusted due to the very good DME flammability. Two additional correction levels were applied, increasing the ignition advance by 3 and 6 CA degrees, compared to the factory settings of the driver. The analysis of the obtained results allowed determining the dependence of the basic engine parameters, in the function of the correction of ignition advance angle. In the summary, attention was also paid to the possibility of determining corrected maps of the ignition advance angle taking into account the variable proportions of fuel components.

Mots clés

  • Dimethyl ether
  • DME+LPG
  • fuel blend
  • SI engine
37 Articles
Accès libre

Operational Verification of a Ship Main Power System Element Choice – Case Study

Publié en ligne: 24 Apr 2020
Pages: 7 - 14

Résumé

Abstract

The article refers to results and conclusions on post-emergency repairs of a turbo-charging system of a DEUTZ engine of the SBV 8M 628 type of 1715 kW – the main power unit of a cement carrier. The failure of the turbocharger led to severing of a part of the exhaust outlet valve head. In order to determine the cause of the turbocharger fault, parametric identification of the reference state of the turbocharging system interacting with the ship main power engine has been carried out. The post-emergency servicing of the turbocharger comprised mounting a new blade rim of expansive instruments of smaller capacity than the so far used. Control measurement results of the power system after the replacement of the turbocharger turbine nozzle have been presented. Limitations of correct engine operation have been noted in the range of maximum load with continuous power (MCR). A range of corrective maintenance servicing of fuel equipment has been presented. Using the values of measured torque at the propeller shaft, incorrect interaction between the shaft and the main engine has been noted. A new propeller, adequate to the design operational parameters of the engine characteristics, has been chosen and mounted. The correctness of turbine expansive instrument replacement has been verified by correct interaction between the elements of the power system: propeller – main engine – turbocharging system. Thus, a wider range of economically acceptable ship operation has been obtained.

Mots clés

  • a ship main power system
  • turbo-charging system
  • operational parameters
  • main engine
  • ship propeller
Accès libre

Analysis of Possibility Limiting the Time of Test Injector in Diesel Engine Using Factory Test Bench Producers of these Elements

Publié en ligne: 24 Apr 2020
Pages: 15 - 20

Résumé

Abstract

Regeneration of parts is the most correct form of use of worn out components and contributes, among others, to reduce CO2 emissions. In the case of elements of fuel injector systems, very high precision is required and such regeneration should be carried out using the original parts. It also requires testing on the original testing stands of these manufacturers, which very often characterized by the fact that it is not possible to perform a short test, which means that it is only possible to perform a time-consuming comprehensive test. An unquestionable advantage in some cases would be the possibility of preliminary verification of the correct operation of the regenerated subassembly without the need for a full time-consuming test. In the present situation, only after completing a time-consuming comprehensive test of the diagnosed element of the injection system, it is often necessary to carry out its disassembly, replacement or correction of one of the components and reassembly with the next time-consuming test. In the case of low unemployment in the labour market, this is extremely unfavourable, and it is often not possible to organize work in such a way that the diagnostic test of the subassembly takes place without the participation of an employee. On the basis of the analyses presented in this article, carried out in the research and development department in company whose employee is one of the co-authors, it can be stated that in the current situation on the labour market where skilled workers are required to work and for the development of science is the most purposeful recognition of the possibility of using vibroacoustic signals to shorten time of tests, which with a high probability may end in a negative result. The preliminary analysis carried out, show that limitation of diagnostic time can be over 35%.

Mots clés

  • transport
  • road transport
  • simulation
  • combustion engines
  • air pollution
  • environmental protection
Accès libre

Slip at Vehicle Transmission System with Hydrokinetic Converter in the Urban Test Cycle

Publié en ligne: 24 Apr 2020
Pages: 21 - 28

Résumé

Abstract

The study concentrated on slip phenomenon occurring at hydrokinetic converter in passenger car transmission system. Optimization of modern automatic transmission systems aims, on the one hand, to further increase the comfort of use, and on the other hand to improve the efficiency and reliability operation of individual components, in such a way as to ultimately result in lowering fuel consumption and also harmful emissions. One of the important factors affecting the mentioned transmissions properties as a whole system is the slip phenomenon occurring between the pump and the hydrokinetic converter turbine. The study presents the results of research on ZF 4HP20 and Fuji Hyper M6 gearboxes operating in vehicle transmission systems. The tests were carried out using the MAHA MSR 500 chassis dynamometer during driving at chosen test cycles. The research covered the transmission systems operating according to selected control algorithms affecting not only the gear shifting strategy but also the operation of the lock up clutch causing the transmissions slip values. As shown by the conducted research, the algorithm controlling the operation of the torque converter can have a significant influence on their operating indexes. The conducted analyses indicate the possibilities of improving the transmission operating indexes, especially in urban driving cycles.

Mots clés

  • hydrokinetic transmission
  • transmission slip
  • test cycle
  • chassis dynamometer
Accès libre

Simulations of the Influence of the Heat Flux at the Shaft Surface of the Conical Slide Bearing on Its Hydrodynamic Lubrication and Operating Parameters

Publié en ligne: 24 Apr 2020
Pages: 29 - 37

Résumé

Abstract

The aim of this work is to investigate, how in the adopted model of hydrodynamic lubrication of a conical slide bearing, the change of the heat flux value at the bearing shaft, affects bearing operating parameters. In this research, the authors use, the known from the literature, Reynolds type equation, describing the stationary hydrodynamic lubrication process of a conical slide bearing. The analytical, solutions, that determine the components of the lubricating oil velocity vector and the equation (analytical solution of energy equation) determining the three-dimensional temperature distribution in the lubrication gap, was also adopted from previous works. In order to obtain numerical solutions, the Newton’s method was used, and the derivatives in the Reynolds type equation were approximated by the finite differences. An application of the method of subsequent approximations allowed considering the influence of temperature, pressure and shearing rate on the viscosity of lubricating oil. The considerations were performed by adopting the Reynolds condition of the hydrodynamic oil film. It was tested, how the assumed value of the heat flux on the bearing shaft surface affects the values of the obtained operating parameters, i.e. the transverse and longitudinal component of the load carrying capacity, friction force and coefficient of friction.

Mots clés

  • hydrodynamic lubrication
  • slide bearing
  • conical bearing
  • heat conduction
  • pressure distribution
  • viscosity
Accès libre

Modelling Method of Dynamic Characteristics of Marine Thin-Walled Structure

Publié en ligne: 24 Apr 2020
Pages: 39 - 46

Résumé

Abstract

Thin-walled structures are very popular in industries, especially in the field of shipbuilding. There are many types of equipment and structures of ships, which are made up of thin-walled structures such as hull, deck and superstructure. Therefore, the analysis and understanding of the static and dynamic characteristics of a thin-walled structure are very important. In this article, we focus on vibration analysis of a typical thin-walled structure-rectangular plate, a basic structure of the hull. Vibration analysis of a rectangular thin plate is conducted by two methods: numerical modelling method of the finite element on Patran-Nastran software platform and experimental method implemented in the laboratory of Gdynia Maritime University. Thin rectangular plate is fixed one end by four clamping plates and is modelled with finite elements and different meshing densities. The numerical model of thin rectangular plate is divided into four cases. Case 1, thin rectangular plate, and clamping plates are modelled with two-dimensional elements. Case 2, the rectangular thin plate is modelled with two-dimensional elements; the clamping plates are modelled with three-dimensional elements. Case 3, both the rectangular thin plate and clamping plates are modelled with three-dimensional elements. Case 4, the rectangular thin plate, and clamping plates are modelled with three-dimensional elements with larger mesh density to increase the accuracy of the calculation results. After that, the results of vibration analysis according to the numerical modelling method on Patran-Nastran software platform for these cases were compared with the measurement results. From there, assess the accuracy of analysis results of selected numerical model methods and the ability to widely apply this numerical model method to other marine structures.

Mots clés

  • Thin-walled structure
  • Vibration
  • FEM
  • rectangular plate
  • Patran-Nastran software
Accès libre

Mechanical Properties of AW-5083 Alloy Joints Welded By Hybrid Method – FSW and MIG

Publié en ligne: 24 Apr 2020
Pages: 47 - 52

Résumé

Abstract

The article presents the research results on the mechanical properties of aluminum alloy AW-5083 and its joints welded by hybrid method – traditional MIG and FSW. AW-5083 alloy is the most currently used in shipbuilding industry. Friction Stir Welding (FSW) – a new technology can be successfully used for butt-welding of different types of aluminum alloy sheets. FSW method can be an alternative to traditional arc welding methods i.e. MIG or TIG. Hybrid welding (FSW with MIG or TIG) could be used in cases when joining only by FSW is not possible. Welding parameters used for the connection of the sheets were presented. Metallographic analysis showed the correct construction of structural bonded joints. The research was carried out using a static tensile test in accordance with the requirements of the Standard PN-EN ISO 4136:2013-05. Flat samples cut perpendicular to the direction of rolling were used. The research was conducted at the temperature of +20ºC. The test shows that the mechanical properties of joints made by hybrid method compered to native material were lower. The tensile strength of joint was lower by 20% then native material 5083 while its yield stress was lower only about 6%. The biggest change was observed in case of plastic properties. Elongation of joint was over 50% lower compared to native material. Despite the decrease of mechanical properties, they meets the requirements of classification societies, so the conclusion is that hybrid method (FSW and MIG) of joining AW-5083 can be applied in shipbuilding industry.

Mots clés

  • hybrid welding
  • Friction Stir Welding (FSW)
  • welding
  • MIG
  • aluminium alloys
  • joints
  • mechanical properties
  • shipbuilding
Accès libre

Distributions of Hydrodynamic Pressure in the Gap of Slide Journal Bearing Lubricated with Ferro-Oil

Publié en ligne: 24 Apr 2020
Pages: 53 - 61

Résumé

Abstract

This research work is part of a broader comprehensive issue, which is the analysis of flow and operating parameters of journal slide bearings lubricated with ferro-oil. In this article, the author presents only the main assumptions and essential transformations of the analytical and numerical model for determining the pressure distributions in the gap of a slide journal bearing lubricated with ferro-oil. It is cardinal that the rheological and magnetic values of ferro-oil parameters adopted in numerical calculations are based on the results of actual values obtained in the author’s earlier research work. There are presented the pressure distributions by abovementioned method in the article for cases of bearings lubricated with ferro-oils with different concentration of magnetic particles. The obtained results are shown in the form of a set of four complementary characteristics of the dimensionless pressure distributions. First and main of them are the calculations for classical Newtonian lubrication but they take into account the influence of the magnetic field on the distributions. The next of the presented characteristics are so-called “corrections” of pressure distribution values, taking into account as follows: effects of changes in ferro-oil viscosity related to temperature changes, impacts of ferro-oil viscosity changes related to pressure changes and the effect of non-oil properties of the lubricant. The article includes a qualitative and quantitative analysis of the obtained results as well as observations and conclusions are presented in it.

Mots clés

  • temperature distribution
  • journal slide bearings
  • ferro-oil
Accès libre

The Development of the World Fleet of Electric Vehicles in Years 2010–2017 with Emphasis on Fuel-Cell Vehicles

Publié en ligne: 24 Apr 2020
Pages: 63 - 68

Résumé

Abstract

The article discusses the development of the world EV fleet in years 2010-2017. Estimates of fleet of plug-in hybrid electric vehicles (PHEV) and BEV in the world are presented. The total number of PHEVs registered in the world in 2016 was roughly 800 thousand (650 thousand in EU). Despite the fact that the sale of electric vehicles has increased considerably in recent years, in particular over 1.1 million in 2017, and also hybrid electric vehicles (PHEV) to approx. 760 thousand in 2017. The article also discusses the development of the electric vehicles market and annual new registrations of vehicles in a breakdown into respective countries. China is the definite leader in this area. In 2017 there were almost twice more BEVs registered in China than in the US and EU together. While the increase in the sale of BEVs in years 2016-2017 in the EU and the US accounted for approx. 50%, it came to over 90% in China. Among eight top worldwide BEV producers, there are four Chinese manufacturers. In the analysed 2017, there were slightly more than 7 thousand of hydrogen-fuelled passenger cars (FCEV) in use, with over 3,500 in the US, 2,300 in Japan and approx. 1,200 in Europe, and several hundred hydrogen-fuelled buses and several dozen hydrogen-fuelled trucks. The article also addresses the development of hydrogen refuelling stations (HRS) in recent years in different countries in the world, bearing in mind that the quantitative development of the hydrogen-fuelled car fleet is strongly associated with the number of hydrogen refuelling stations.

Mots clés

  • passenger cars
  • electric vehicle
  • fuel cells
  • hydrogen
  • environment
Accès libre

Comparative Preliminary Unit Costs Analysis of the Operation of Passenger Cars with Combustion Engines and Fuel Cell Vehicles Powered by Hydrogen

Publié en ligne: 24 Apr 2020
Pages: 69 - 74

Résumé

Abstract

The article presents political and legal aspects regarding the recommendation for the development of hydrogen technology in the economy and in transport. The development of electric cars with hydrogen-powered fuel cells, which took place in recent years in the world, has been outlined. The principles of calculation of average vehicle operating costs applicable in the transport economics are discussed. The estimated average unit operating costs of a statistical passenger car using conventional energy carriers, estimated in the studies of the Motor Transport Institute are quoted. The assumptions and results of the estimation of the average cost per 1 vehicle-kilometre of the electric passenger car’s mileage (BEV) have been presented, as well as the assumptions and results of the estimation of the average unit operating costs of a hydrogen powered passenger car (FCEV). The average unit costs of the mileage of these vehicles have been compared. The predictions regarding the future changes in the average prices of FCEV vehicles have been cited and the average unit costs of operating electric cars with fuel cells by the 2050 have been estimated. The project of administrative support for the development of low-emission transport in Poland was indicated.

Mots clés

  • passenger cars
  • fuel cells
  • hydrogen
  • costs
Accès libre

Self-Learning Control Algorithms Used to Manage the Operating of an Internal Combustion Engine

Publié en ligne: 24 Apr 2020
Pages: 75 - 82

Résumé

Abstract

The article presents the possibility of using self-learning control algorithms to manage subassemblies of an internal combustion engine in order to reduce exhaust emissions to the natural environment. In compression ignition (CI) engines, the issue of emissions mainly concerns two components: particulate matter (PM) and nitrogen oxides (NOx). The work focuses mainly on the possibility of reducing the emission of nitrogen oxides. It is assumed that the particularly problematic points when it comes to excessive emission of harmful substances are the dynamic states in which combustion engines operate constantly. In dynamically changing operating points, it is very difficult to choose the right setting of actuators such as the exhaust gas recirculation (EGR) valve to ensure the correct operation of the unit and the minimum emission of these substances. In the light of the above, an attempt was made to develop a self-learning mathematical model, which can predict estimated emission levels of selected substance basing on current measurement signals (e.g. air, pressure, crankshaft rotational speed, etc.). The article presents the results of the estimation of nitrogen oxides by the trained neural network in comparison to the values measured with the use of a sensor installed in the exhaust system. The presented levels of estimated and measured results are very similar to each other and shifted over time in favour of neural networks, where the information about the emission level appears much earlier. On the basis of the estimated level, it shall be possible to make an appropriate decision about specific settings of recirculation system components, such as the EGR valve. It is estimated that by using the chosen control method it is possible significantly to reduce the emission of harmful substances into the natural environment while maintaining dynamic properties of the engine.

Mots clés

  • transport
  • simulation
  • combustion engines
  • environmental protection
  • neural network
Accès libre

Validation of Microscopy Measured Porosity in Carbon Fibbers Composites

Publié en ligne: 24 Apr 2020
Pages: 83 - 90

Résumé

Abstract

One of the most common defects in carbon fibre reinforced plastics (CFRP) is porosity. Too much of those defects could be serious problems to mechanical properties, which directly take effect on elements safety, like aircrafts. Therefore, the evaluation of porosity is very important test. Microscopic observations are widely used as a quality instrument in materials and constructions inspections. Cross section image of a material is easy to prepare and analyse. Porosity of a carbon fibre reinforced plastic can be clearly spot in such kind of images. Study shows that in the most cases porosity appear between layers of fibres, rather between fibres. Unfortunately, image from microscope is only 2D picture from a small representative region. Because of that, comparison of 2D image to a real porosity distribution in all volume of a material is very difficult. To verify 2D microscopic observation method is necessary to perform another kind of tests. In this article, authors focused on non-destructive (NDT) and destructive testing methods. 2D porosity images from light microscope were compared with three different testing methods: ultrasonic test (UT), computed tomography (CT) test and constituent content of composite materials standard test method according to ASTM D3171 – 15, procedure B. Porosity results obtained from dissolution of resin from the carbon-epoxy resin sample.

Mots clés

  • porosity
  • carbon fibre
  • microscope
  • UT (Ultrasonic test)
  • CT (computed tomography)
Accès libre

Energy Balance of a Vehicle Equipped with Hybrid Propulsion System Fuelled with Alternative Fuels

Publié en ligne: 24 Apr 2020
Pages: 91 - 96

Résumé

Abstract

Article presents the energetic balance of small-unmanned vehicle hybrid power transmission. The vehicle equipped with serial hybrid transmission consisted of electric engines connected to the battery pack and small Diesel power generator. In mentioned construction, battery is used as energy buffer and combustion engine is used more as emergency power supply, and is turned on when battery is depleted. In other condition, power generator can be turned off, without reducing power of transmission parameters, except its range. Vehicles with hybrid drive are very common chosen vehicles by users. More and more often, we also talk about searching for replacement fuels for internal combustion engines, so also for those with hybrid drive. The research was carried out on an unmanned land platform equipped with a hybrid propulsion system supplied as standard with Diesel oil. The article presents the problems of comparing the efficiency of a hybrid vehicle fuelled with Diesel oil, but also with alternative fuels based on kerosene and other components. For test, three types of fuels were used, standard Diesel oil, F-34 and with experimental mixture of Jet A-1 fuel with 10% of 2-ethylhexanol. Energy used for charging of the battery, from tank-to-wheel, was calculated. This also enables to calculate total efficiency of such hybrid power transmission, powered with different fuels.

Mots clés

  • energy balance
  • unmanned vehicle
  • hybrid transmission
  • test stand
Accès libre

Analysis of Electric Vehicles Efficiency and their Influence on Environmental Pollution

Publié en ligne: 24 Apr 2020
Pages: 97 - 104

Résumé

Abstract

Electric vehicles are increasingly present on the roads of the whole world. They have the opinion of ecological vehicles, not polluting the environment. Society is more and more often persuaded to buy electric cars as an environmentally friendly solution but is this for sure? Electric cars need quite a lot of electricity accumulated in batteries to drive on a long range. During the charging process, this energy is obtained from the electricity network, to where it is supplied by power plant. Electricity production from renewable sources is a privilege for the rare. However, electric cars are charged from the electricity grid, which in large part energy comes from non-renewable fuels. The efficiency of energy production in power plants and the energy transmission and conversion chain causes that only part of the energy produced in this way goes to the vehicle’s wheels. Although the power plants are equipped with more and more efficient exhaust gas cleaning systems, they do not clean them up to 100%. Sulphur, nitrogen, mercury and heavy metals remain in the exhaust. The article is an attempt to answer the question whether the total emission of toxic components associated with the use of an electric vehicle is not bigger than in a traditional internal combustion engine.

Mots clés

  • electric vehicle
  • exhaust gas toxic components
  • electro power plants
  • electricity production
Accès libre

Determination of Material Characteristics Necessary for Modelling of Marine Structures Exposed to Small-Calibre Bullet

Publié en ligne: 24 Apr 2020
Pages: 105 - 111

Résumé

Abstract

The article presents the results of tests of impact properties of steel 1.3964 used on the construction of modern mine destroyers. Ships of this type, like any other military unit, may be exposed to small-calibre projectiles. Firing can be done, for example, from aircraft, drones or pirate units. The thickness of the plates used in the ship’s construction does not guarantee effective resistance to the projectile calibre 7.62 mm for all compartments of such ships. Thus, it is possible to modify the existing structure or apply additional solutions that will ensure a certain level of ballistic resistance. Solutions of this type are necessary in order to maintain the stability and buoyancy of the ship at the current level. During the tests, a stress-strain curve for steel 1.3964 was obtained, then the Johnson-Cook plasticity and damage model was proposed, which was used in the FEM simulation. The task was modelled as non-linear considering the deformation of both the sample and the projectile. The simulation was prepared in the CAE program, and then verified by an experiment on the shooting range. The results were presented in the form of diagrams and deformation figures, and were compared with photographs of samples and velocities after the specimen.

Mots clés

  • sea constructions
  • CAE
  • marine mine destroyer
Accès libre

Using Sorbents for Oil Spill Clean-Up in Ports and Coastal Areas

Publié en ligne: 24 Apr 2020
Pages: 113 - 117

Résumé

Abstract

Petroleum substances are a mixture of many hydrocarbons of various structures; some of them are toxic for marine organisms. In case of pollution of the aquatic environment, these compounds may enter seawater organisms and adversely affect gas exchange and inhibit photosynthesis. Therefore, it is important to take measures to reduce the emissions of these compounds into the aquatic environment and quickly to remove possible spills of uncontrolled pollution. Sorbents are materials that soak up oil from water. They are best suited for the absorption of oil – derived substances. They are used to absorb leaks in open and closed tanks, particularly in hard – to-reach places. Sorbents can be natural organic, natural inorganic or synthetic. Natural sorbents are divided to organic materials such as peat moss or wood products, and inorganic materials such as vermiculite or clay. Sorbents are available in a loose form, which includes granules, powder, chunks and cubes. Synthetic sorbents are used to wipe other oil spill recovery equipment such as skimmers and booms after a spill clean-up operation. The thesis deals with the issues related to the analysis of the possibility of using sorbents to combat oil pollution in port and coastal areas. The article discusses the types of pollution occurring in coastal waters, as well as the types of sorbents used and the forces and measures to combat pollution. The characteristic features of sorbents are rate of absorption and adsorption, oil retention and ease of application. Absorption tests were carried out and the best sorbents for combating oil pollution were selected.

Mots clés

  • materials engineering
  • maritime engineering
  • fuel
  • oils & lubrication
Accès libre

Influence of Inlet Geometry on the Efficiency of 1 MW Steam Turbine

Publié en ligne: 24 Apr 2020
Pages: 119 - 126

Résumé

Abstract

The process of the design of the 1 MW steam turbine includes designing the stator and rotor blades, the steam turbine inlet and exit, the casing and the rotor. A turbine that operates at rotation speeds other than 3000 rpm requires a gearbox and generator with complex electronic software. This article analyses the efficiency of eight turbine variants, including seven inlet geometries and three stages of stator as well as an eight variant with one of the inlets, all three stages and an outlet.

This article analyses the efficiency of 8 turbine variants, including four spiral inlet geometries and tree stages in a 1 MW steam turbine. In the article, inlets and 1st stator blades of various geometries were analysed to obtain maximal turbine efficiency. Changing the inlet spiral from one pipe to two pipes increased the turbine efficiency. The geometry of the blades and turbine inlets and outlet was carried out using Design Modeller. The blade mesh was prepared in TurboGrid and inlet in ANSYS Meshing.

Mots clés

  • turbine engine
  • steam turbine
  • turbine inlet
Accès libre

Technical and Ecological Analysis of Different Solutions of the Power Supply of a Marine Diesel Engine

Publié en ligne: 24 Apr 2020
Pages: 127 - 134

Résumé

Abstract

The article contains provisions on the prevention of sea pollution by ships, including, inter alia, the International Convention for the Prevention of Pollution from Ships, developed in 1973 (MARPOL). The convention aims to protect the marine environment from oil and its derivatives. Special areas, where extraordinary measures have been taken to prevent sea pollution, due to the intensity of ship traffic and the greater threat of damage to the marine environment have also been presented. In the further part of the article, the applicability of various pro-ecological solutions, i.e. the use of catalysts, low-sulphur fuels, and in the case of using residual fuels – exhaust gas scrubbers were described. In the main part of the article, a technical and ecological analysis was made. In addition, difficulties resulting from the use of pro-ecological solutions were described. The costs of using low-sulphur fuel meeting the emission standards, installing the scrubber and modification of the natural gas combustion unit were compared with the assumption of ten years of passenger-car ferry sailing. Then the problems that individual solutions create were shown. In the final part of the article, alternatives to those described, i.e. the liquefied natural gas (LNG) power supply, electric and hydrogen drives were presented.

Mots clés

  • technical analysis
  • special areas
  • exhaust gas scrubbers
  • alternative drives
Accès libre

Composite Materials for Warship Constructions

Publié en ligne: 24 Apr 2020
Pages: 135 - 140

Résumé

Abstract

The article presents the basic properties of composite materials used for the construction of special ships. Static and dynamic characteristics of materials such as wood and polyester-glass composites are presented. Noteworthy are materials such as surface modified wood and polyester-glass composites with the addition of recyclate. Composite materials are widely used materials for the construction of non-magnetic warships. The article describes the properties of surface modified wood with polymethyl methacrylate and a polyester-glass composite with the addition of recyclate. The recyclate is fragmented, milled polyester-glass scrap. The content of the recyclate greatly affects the mechanical properties of the composite. The properties of the composite with the addition of recyclate depend on the recyclate content as well as the production technology and size of the recycled granulates. The test results showed that the increase in the recycled content causes a decrease in the mechanical properties of the composite. However, it should be remembered that these materials originated from waste, waste that is not subject to self-degradation, which have a very negative impact on the natural environment. At present, where there is a very large pollution of the natural environment, the processing and management of huge amounts of composite waste is an essential goal. A significant amount of recyclate significantly reduces the mechanical properties of the composite; however, the same large amount of recycled material has been transformed and used. The manufactured material and its structural elements are still non-magnetic structures and can be used on a less loaded element. The choice of material for the construction of special ships elements is determined not only by its properties but also by knowledge, experience, method of processing, economic and technical risk.

Mots clés

  • polyester-glass composites
  • recyclate
  • modified wood
  • non-magnetic warships isotropic
Accès libre

The Influence of Cutting Parameters on Surface Topography During Turning Marine Pump Shafts

Publié en ligne: 24 Apr 2020
Pages: 141 - 148

Résumé

Abstract

One of the greatest problems of modern production techniques is the achievement of an appropriate quality at minimal costs and accompanied by the production efficiency increase. Therefore, while designing the production process. The technology used should have a considerable influence on the durability and reliability of machine parts to be produced. During finish treatment, the final dimensions as well as functional properties are imparted to a given element by application of proper treatment type. The engineer has a range of production techniques to choose for the proper surface layer formation. Conventional turning machines belong to the basic equipment of ships, because in sea conditions, they enable the execution of a spare part or carrying out the necessary operations in the process of their regeneration. The use of modern cutting tools makes it possible to obtain a surface with low values of surface roughness parameters. The use of new generation cutting inserts on conventional lathes can cause problems for operators. The lack of the ability to ensure proper of treatment condition and setting errors of cutting tools contribute to the damage of the cutting insert or the surface of the workpiece. The article presents the results of influence of different cutting parameters on surface topography during turning process of stainless steel. A shaft made of 304L stainless steel was used for the research. The cutting process was carried out on a universal TUM 25B x 500 centre lathes. During the turning the following machining parameters were used: cutting speed Vc [m/min], feed f [mm/rev] and depth of cut ap [mm].The turning process was conducted by a cutting tool with CCGT 09T302 UM, CCGT 09T304 UM and CCGT 09T308 UM inserts. Measurement of surface topography was carried out by T8000 profilometer.

Mots clés

  • finish turning process
  • surface topography
  • cutting parameters
  • stainless steel
Accès libre

Comparative Analysis of Fuels Derived from PE Plastic Waste with a Mixture of Plastic Recycling Waste of Codes: 1, 2, 4, 5, 6 and 7 Based on Low-Temperature Pyrolysis

Publié en ligne: 24 Apr 2020
Pages: 149 - 154

Résumé

Abstract

Thanks to their numerous advantages, plastics are becoming more and more widely used in all branches of industry. The quantities of products, their packaging and, consequently, the amount of synthetic polymer waste are steadily increasing, what poses a high risk to the environment due to their long decomposition time. To reduce waste production is practically impossible, therefore it is very important to constantly implement new and improve existing methods of waste treatment. The following article presents one of the alternative methods for synthetic polymer waste treatment, which is low-temperature pyrolysis. Two pyrolysis processes were carried out. During the first experiment a polyethylene plastic material was used, in the second experiment a mixture of typical household recycling waste of codes 1, 2, 4, 5, 6, and 7 were tested. During the thermal processing, the input material undergoes a chemical transformation due to breaking of long hydrocarbon chains. At the same time, high-energy density products, such as petroleum products and gas, are produced. The main advantage of the presented method is that it allows reducing preliminary technological processes to a minimum and it is easily automated, as it reduces the process to one compact installation. The reduction of the amount of stored waste and the recovery of petroleum derivatives, are additional advantages of pyrolysis implementation. That, in consequence allows reducing consumption of fossil fuel resources.

Mots clés

  • pyrolysis
  • plastics
  • waste
Accès libre

Application of Similarity Method of Distance Courses Describing the Elements Content in Cement Concrete After 50 Forced Thermal Cycles

Publié en ligne: 24 Apr 2020
Pages: 155 - 162

Résumé

Abstract

The article presents material solution based on the application of ceramic dust as concrete mix component intended for airfield pavements. The applied dust influences the changes in internal structure of concrete composite. Diversification of internal microstructure of cement concrete using the suggested dust has significant influence on the improvement of compressive strength. The laboratory analyses included concretes curing in standard conditions and concretes subject to thermal cycles representing the destructive influence of imposed loading. Comparative SEM observations of concretes subject to 50 thermal cycles proved significant influence of dust on internal structure of composite. In the study 6 samples were selected, which, each time, were intended for the laboratory tests. The applied similarity analysis of distance courses in case of this concrete. Similarity indexes between input and target sequence were defined. Diagrams presenting the similarity of the analysed concretes were prepared (after 28 days of curing and after 50 thermal cycles). It was proved that the suggested method can be used to assess the elements content and define the similarity of concrete intended for airfield pavements in the selected of areas (cement matrix, contact area between fine aggregate and cement matrix, contact area between coarse aggregate and cement matrix and contact area between air voids and cement matrix).

Mots clés

  • cement concrete
  • airfield pavement
  • analysis of similarity
  • forced thermal cycles
Accès libre

Application of Similarity Method of Distance Courses Describing the Elements Content in Typical Cement Concrete After Thermal Cycles

Publié en ligne: 24 Apr 2020
Pages: 163 - 170

Résumé

Abstract

The work concerns the use of similarity analysis of distance course. Composition of concrete mixes was designed. The cement concrete composition includes cement, coarse aggregate, fine aggregate, water and admixtures. The laboratory analyses included concretes curing in standard conditions and concretes subject to thermal cycles representing the destructive influence of imposed loading. Laboratory tests assumed the fifty thermal test cycles. A single test cycle included process of alternate heating and cooling. Recurrent influence of temperature stimulated the impact of aircraft on airfield pavements. The assumed heating and cooling time corresponded to the time during which the aircraft effected the most frequently used airfield pavement within the area of Poland. Comparative SEM observations of concretes subject to thermal cycles were conducted. An increase in the width of microcracs has been observed. In case of crystallization, there is diversification within the area of cement matrix, contact area between cement matrix and aggregate grains and in case of porosity characteristics of both concretes. Similarity indexes between input and target sequence were defined. Diagrams presenting the similarity of the analysed concretes were prepared (after 28 days of curing and after thermal cycles). It was proved that the suggested method could be used to define the similarity of concrete intended for airfield pavements.

Mots clés

  • cement concrete
  • airfield pavement
  • analysis of similarity
  • thermal cycles
Accès libre

Operating Parameters of a Slide Bearing with Parabolic-Shaped Slide Surfaces with Consideration of the Stochastic Changes in the Lubrication Gap Height

Publié en ligne: 24 Apr 2020
Pages: 171 - 178

Résumé

Abstract

In this article, the authors present the equations of the hydrodynamic theory for a slide bearing with parabolic-shaped slide surfaces. The lubricating oil is characterized by non-Newtonian properties, i.e. an oil for which, apart from the classic oil viscosity dependence on pressure and temperature, also an effect of the shear rate is taken into account. The first order constitutive equation was adopted for considerations, where the apparent viscosity was described by the Cross equation. The analytical solution uses stochastic equations of the momentum conservation law, the stream continuity and the energy conservation law. The solution takes into account the expected values of the hydrodynamic pressure EX[p(ϕ,ζ)], of the temperature EX[T(ϕ,y,ζ)], of the velocity value of lubricating oil EX[vi(ϕ,y,ζ)], of the viscosity of lubricating oil EX[ηT(ϕ,y,ζ)] and of the lubrication gap height EX[εT(ϕ,ζ)]. It was assumed, that the oil is incompressible and the changes in its density and thermal conductivity were omitted. A flow of lubricating oil was laminar and non-isothermal. The research concerned the parabolic slide bearing of finite length, with a smooth sleeve surface, with a full wrap angle. The aim of this work is to derive the stochastic equations, that allow to determine the temperature distribution, hydrodynamic pressure distribution, velocity vector components, load carrying capacity, friction force and friction coefficient, in the parabolic sliding bearing, lubricated with non-Newton (Cross) oil, including the stochastic changes in the lubrication gap height. The paper presents the results of analytical and numerical calculation of flow and operating parameters in parabolic sliding bearings, taking into account the stochastic height of the lubrication gap. Numerical calculations were performed using the method of successive approximations and finite differences, with own calculation procedures and the Mathcad 15 software.

Mots clés

  • hydrodynamic lubrication
  • analytical stochastic principles and solutions
  • apparent viscosity
  • numerical calculation
  • load carrying capacity
  • friction force
Accès libre

The Experimental Investigation of Surface Roughness After Dry Turning of Steel S235

Publié en ligne: 24 Apr 2020
Pages: 179 - 184

Résumé

Abstract

Nowadays lot of scientific work inspired by industry companies was done with the aim to avoid the use of cutting fluids in machining operations. The reasons were ecological and human health problems caused by the cutting fluid. The most logical solution, which can be taken to eliminate all of the problems associated with the use of cooling lubricant, is dry machining. In most cases, however, a machining operation without lubricant finds acceptance only when it is possible to guarantee that the part quality and machining times achieved in wet machining are equalled or surpassed. Surface finish has become an important indicator of quality and precision in manufacturing processes and it is considered as one of the most important parameter in industry. Today the quality of surface finish is a significant requirement for many workpieces. Thus, the choice of optimized cutting parameters is very important for controlling the required surface quality. In the present study, the influence of different machining parameters on surface roughness has been analysed. Experiments were conducted for turning, as it is the most frequently used machining process in machine industry. All these parameters have been studied in terms of depth of cut (ap), feed rate (f) and cutting speed (vc). As workpiece, material steel S235 has been selected. This work presents results of research done during turning realised on conventional lathe CDS 6250 BX-1000 with severe parameters. These demonstrate the necessity of further, more detailed research on turning process results.

Mots clés

  • dry turning
  • turning parameters
  • turning results
  • surface roughness
  • arithmetic average surface roughness value
Accès libre

Solutions in the Vehicle Suspension

Publié en ligne: 24 Apr 2020
Pages: 185 - 196

Résumé

Abstract

The paper presents a review of the suspension solutions used on the street vehicle up to the now a days, finalising with presentation of their damping characteristics and with evaluation of their advantages or disadvantages. Long time the suspension systems have been dominated by the classic passive suspensions realized with metallic springs, shock absorbers with constant damping coefficients and anti-roll bars, excepting some luxury and sport cars using semi-active and active suspensions. There are presented some semi-active suspension solutions with continuous or discontinuous damping characteristics adjustment and the evolution of the Citroen and other active suspensions. All of them improve in some matter the performances but all of them have not ability to recuperate energy and has auxiliary energy consumption so last period the electromagnetically shock absorbers are researched, the paper presenting some of them. The paper also presents magneto rheological MR damper, solutions for adjustable passive shock absorbers and solutions for passive shock absorbers with variable damping coefficient with the stroke, e.g. Monroe Sensa Trac, Citroën Solution and VZN solution, with their damping characteristics and performances.

Mots clés

  • active suspension
  • semi-active suspension
  • comfort
  • stability
  • clearance
  • progressive cushions
  • VZN
Accès libre

Effect of the Recyclate on a Deflection of Composites in Bending

Publié en ligne: 24 Apr 2020
Pages: 197 - 203

Résumé

Abstract

The aim of the research was to determine the effect of polyester-glass recyclate on the deflection of composite samples subjected to three-point bending. The polyester-glass recyclate was obtained from the part of the ship’s hull made of polyester-glass composite, constituting scrap metal. The pieces of scrap were pre-fragmented and then processed into a prepared stand for this purpose. Such a fragmented recycling will be used to make composites with different scrap / recycled content. For this purpose, research materials were made using the vacuum bag method with the percentage of 0%, 10% and 20% recyclate) as well as various granulation (i.e. 1.2 mm and 3.0 mm). The research material consisted of rectangular plates with a thickness corresponding to the thickness of the samples. The samples for testing were made by water cutting. The tests were carried out on a suitably prepared stand, which was made of a universal Zwick Roell testing machine and three-point bending handles and a dial indicator. The spacing of the supports has been determined in accordance with the binding standard for three-point bending. Obtained results from tests, i.e. strain, stress, deflection, deformation allowed analysing the impact of recyclate on bending strength and defining the deflection arrow. Based on the results obtained from three-point bending, it can be concluded that the polyester-glass recycling has an influence on the decrease of strength, stress and deflections of the tested composites.

Mots clés

  • recycling
  • three-point bending
  • composites
  • new materials
  • force-strain curves
Accès libre

Numerical Investigation of Endplates Influence on the Wing in Ground Effect Lift Force

Publié en ligne: 24 Apr 2020
Pages: 205 - 210

Résumé

Abstract

The article presents a comparison of the wing in ground effect magnitude of conceptual WIG craft model main characteristics for a wing with and without endplates which are also known as winglets in regular aircraft. In article, the author describes WIG effect with and WIG craft, which operates on low altitude, smaller than the length of wing chord, mostly above the water reservoir. WIG effect phenomenon is simple. The first aircraft needs to fly at adequate altitude, with a smaller distance between lower airfoil surface and ground static pressure rises, leading to rising of lift force. The main advantage of the wing in ground effect craft on regular aircraft is a much higher lift to drag ratio, also this phenomenon provides to drop in specific fuel consumption of aircraft and allows flying with heavier cargo due to higher lift force. Characteristics present in the article were designated from simulations, which were conducted in Ansys Fluent software. Results obtained for a wing with endplate in numerical analysis shows the superiority of this approach. Endplates provide to increase WIG effect by a decrease in induced drag through the move out vertices from the wing tips, which are made by differential pressure above and under the wing. As winglets in regular aircraft, endplates provide to save fuel. WIG craft does not need airports so it could be a cheap alternative for modern aircraft.

Mots clés

  • endplates
  • ekranoplan
  • numerical analysis
  • wing in ground effect
  • airfoil
Accès libre

Investigation of Thermal Properties of Novel Phase Change Material Mixtures (Octadecane-Diamond) with Laser Flash Analysis

Publié en ligne: 24 Apr 2020
Pages: 211 - 218

Résumé

Abstract

Phase change materials (PCMs) are widely used in numerous engineering fields because of their good heat storage properties and high latent heat of fusion. However, a big group of them has low thermal conductivity and diffusivity, which poses a problem when it comes to effective and relatively fast heat transfer and accumulation. Therefore, their use is limited to systems that do not need to be heated or cooled rapidly. That is why they are used as thermal energy storage systems in both large scale in power plants and smaller scale in residential facilities. Although, if PCMs are meant to play an important role in electronics cooling, heat dissipation, or temperature stabilization in places where the access to cooling water is limited, such as electric automotive industry or hybrid aviation, a number of modifications and improvements needs to be introduced. Investigation whether additional materials of better thermal properties will affect the thermal properties of PCM is therefore of a big interest. An example of such material is diamond powder, which is a popular additive used in abradants. Its thermal diffusivity and conductivity is significantly higher than for a pure PCM. The article presents the results of an analysis of the effect of diamond powder on thermal conductivity and diffusivity of phase change materials in the case of octadecane.

Mots clés

  • phase change materials
  • PCM
  • diamond powder
  • thermal conductivity
  • thermal diffusivity
Accès libre

Analysis of the Vehicle Exploitation Process with Regard to Profiling

Publié en ligne: 24 Apr 2020
Pages: 219 - 225

Résumé

Abstract

Transport telematics systems integrate information technology with telecommunications for their use in various transport systems. Thanks to the use of advanced technical solutions and modern telecommunications and IT systems, it is possible to implement additional innovative services. They can be used to rationalize the process of using and maintaining means of transport. Modern vehicles are equipped with telematic on-board systems. Such solutions combine various electronic devices used in the vehicle. For this purpose, bus solutions are used, thanks to which it is possible to control individual systems and devices. It is also possible to use the transmitted data to detect negative exploitation phenomena during vehicle use (e.g. glazing phenomenon, work in the upper engine rev range with too low coolant temperature, intensive work compressor of the high air pressure system being a symptom of inability of pneumatic systems). This is possible because the data being sent has a specific information resource. Thanks to this, to can be concluded about the loss of the exploitation potential of the vehicle. This approach will be used to rationalize the technical service of the vehicle fleet, with regard to profiling. Using exploitation data, received via a telematic interface from vehicles, it is possible to profile the rolling stock. It consists in distinguishing individual sets of vehicles due to certain reliability and exploitation properties. This approach allows for the specification of the rolling stock exploitation, giving the opportunity to rationalize the use and exploitation. The publication presents the author’s graph of the exploitation process taking into account the profiling of the vehicle fleet. The application of the presented approach will contribute to the improvement of the value of certain vehicle reliability and exploitation indicators.

Mots clés

  • transport telematics systems
  • exploitation
  • reliability
Accès libre

Modelling of Transport System Operational Reliability a Markov Approach

Publié en ligne: 24 Apr 2020
Pages: 228 - 234

Résumé

Abstract

The workability of a transport system is associated with performance and operational reliability. Operational reliability provides a measure of the probability that a transport system will realize transport process as intended. Performance reliability is an adequacy measure of transport process realization under specific environmental and traffic conditions. Transport system can be modelled as repairable, multistate, non-homogenous rectangular or dendrite system. This article provides the Markov and semi Markov models for estimation of the operational and performance reliability of city transport system. The system is semi homogenous it means that serial subsystems have the same reliability function. The reliability of any serial subsystem is exponential. The distribution of the repair time is any probability distribution. In case where the probability distribution of the repair time is exponential, the Markov process is used to construct simulation model. The simulation model was applied at Microsoft Excel. Many stochastic models in engineering, logistic and even finance or insurance are setup in a spreadsheet for simulation. The semi Markov model of the multistate reliability of repaired system is applied to the street system. The embedded Markov chain was used to count stationary probabilities. The possibility of application of the results is illustrated by an example for the systems with rectangular or dendrite shaped accordingly, consist of three types of elements.

Mots clés

  • transport
  • road transport
  • simulation
  • Markov model
  • semi Markov model
Accès libre

Anomaly of Rotor Dynamics in Ultra-Light Helicopter – Robinson R22

Publié en ligne: 24 Apr 2020
Pages: 235 - 239

Résumé

Abstract

The article presents the analysis of anomaly of rotor dynamics in ultra-light helicopter - Robinson R22. Robinson R22 is two-seat, two-blade main rotor and single-engine helicopter, well known as simple and common used aircraft because of low price and high availability. At the same time, large number of accidents and strictly defined rules (recommended piloting technique) and weather condition for safe flight show disadvantages of Robinson R22. The reason for considering this topic is the analysis of different flight properties and helicopter behaviour as well as easy entering into dangerous flight manoeuvre. In the article different flight properties and loss of control during the pull-up, manoeuvre or vertical gusts of wind and mast bumping accidents were analysed. Analysis shows that problem may be caused by construction of three-hinged rotor hub, designed and patented by F. Robinson. Article presents model of rotor hub and review of main rotor and rotor hub construction in light helicopters. Because of number of accidents, caused by the unusual behaviour of Robinson R22, restrictive pilotage rules were introduced: prohibition of flight in certain weather conditions, the necessity of attending additional training conducted by trained instructors. To reduce the probability of an accident a special instruction for specific Robinson R22 properties was created. Moreover, the statistics of accidents resulting from loss of control and review of legal changes caused by Robinson R22 accidents are presented.

Mots clés

  • rotor hub
  • Robinson R22
  • helicopter
  • the pull-up manoeuvre
  • rotor dynamics
Accès libre

Introduction to the Examination of Thin-Walled Structures Using the Vibrodiagnostic Method

Publié en ligne: 24 Apr 2020
Pages: 242 - 248

Résumé

Abstract

The article presents a methodology of non-destructive diagnostic vibratory tests of welded plates with geometrical parameters that classify them into a group of thin-walled panels. On the basis of such plates, most ship constructions are created. In previous works, the authors dealt with the study of welded joints in plates with significant thicknesses and developed for them a number of methods for assessing the quality of welded joints. Vibrodiagnostics is a NDT method that allows the use of a variety of techniques and tools. It enables measurements to be made in both a contact and non-contact way depending on the requirements of the structure and the environment. Vibrodiagnostic method is one of the most modern NDT methods, which uses modern measurement tools and computer analysis of data. On the basis of the developed methods, the authors intend to verify their application to plates from real welded constructions, which will be performed in typical shipyard conditions by welders. Such tests are important due to their use for the construction of a real SHM ship construction monitoring system. These methods allow for the examination of the condition of ships’ structural plates and can detect defects in welded joints that prevent ships from operating under severe sea conditions. The article presents the laboratory stand, the sensor layout, results, and their initial analysis.

Mots clés

  • welding
  • welded joints
  • non-destructive testing
  • vibrations
  • time – frequency characteristics
Accès libre

Numerical Investigations of Stress Concentration in Reinforcement Steel Structure by Composite Overlays

Publié en ligne: 24 Apr 2020
Pages: 249 - 256

Résumé

Abstract

The stress concentration observed in the vicinity of cut-outs and holes in structural elements significantly influences the fatigue endurance of machines subjected to cyclic loads. Numerous studies have been made so far to improve this situation and increase the structure lifetime. Several design recommendations have also been worked out to avoid the problem of premature failure. The proposed article illustrates the influence of the composite overlays applied around the cut-outs made in flat steel constructional elements subjected to axial tension. The detailed study concerns the reinforcement made from the FRP (fibre reinforcement polymer) composite applied around the notches. Two types of composite materials were used, namely: TVR 380 M12/R-glass (glass fibres embedded in epoxy resin matrix) and AS4D/9310 (carbon fibres embedded in epoxy resin matrix). In the first step, the detailed numerical studies (finite element analysis) were performed for the steel samples (with no overlays added) with cut-outs made in the form of circle, square and triangle hole (the last two with rounded corners). The results of these studies were compared with the existing analytical solutions with respect to the stress concentration factors (SCF) estimation. The relatively good conformity was observed when using dense meshes of finite elements placed around the void vicinity. In the next step, the composite overlays were applied around cut-outs and their influence on the stress concentration was investigated. The influence of the fibre orientation, numbers of layers, sizes of the composite overlay used were considered. It was proved that the application of composite overlays evidently decreases the stress concentration around the notches.

Mots clés

  • plate
  • hole
  • cut-out
  • stress concentration
  • FRP composite
  • reinforcement
  • FEM
Accès libre

Storage of Wind Power Energy

Publié en ligne: 24 Apr 2020
Pages: 257 - 264

Résumé

Abstract

There has been a big increase in production and investments in wind turbines and wind farms in last 20 years. New generation of wind turbines is more reliable than from 1980’s are, which necessary condition is energy production is to play an important role among renewable energy sources. Over the last 30 years, the size of wind turbines increased 7 times, as nominal power increased nearly 14 times. At present, turbines capable of producing over 10 MW of power are being developed. The main reason for continued growth of turbines sizes is to minimize the energy cost per kilowatt-hour. However, it is worth remembering that according to the „square-cube law”, there is a maximum size after the surpassing of witch the cost of ever-larger turbines would grow faster than financial gain from the increased size. In this article, authors present energy storage methods and devices for wind power plants and cost-effectiveness of the individual energy storage methods. Authors also present data about energy storage efficiency and groups of energy storage devices for wind power plants such as: compressed-air power stations + gas turbine (CAES), utilizing underground wells, pumped storage power plants, rechargeable batteries (lithium-ion, lead-acid, sodium sulphur, VRB, zinc-flow, zinc-air, zinc-air), flywheels, hydrogen production and storage systems, superconducting magnetic energy storage (SMES), electrostatic storage – electrolytic capacitors.

Mots clés

  • energy storage
  • wind energy
  • renewable energy
  • energy storage methods
Accès libre

Analysis of Possibility of Repairing Welding of Selected of the Steam Turbines

Publié en ligne: 24 Apr 2020
Pages: 265 - 271

Résumé

Abstract

The article presents the results of the study on the possibilities of repair by welding methods of exploitation steam turbine bodies. Two hull were investigation after a lifetime of more than 200.000 hours. Repair welding study were carried out on the L17HMF cast steel body in the immediately after exploitation condition, whereas the L21HMF cast steel body underwent a revitalization after the exploitation, and then the welding repair research were performed. On the material taken from the L17HMF cast steel hull, welding repairs were made by welding the previously cut four grooves measuring 200 mm 50 mm 50 mm, which were simulations of material defected. All samples were made in areas where maximum steam temperatures were operating. Welds were tested with destructive and non-destructive methods to determine their quality and define non-compliances detected. The L21HMF cast steel was subjected to a revitalization process, which consisted the hull in subjecting heat treatment in order to obtain favourable structural changes and improve the strength properties. Non-destructive examinations and hardness tests were carried out on the remedial weld, indicating the required quality of repairing remedial weld. Comparative study is aimed at demonstrating the main welding problems during the repair welding of exploitation steam turbine hulls.

Mots clés

  • regenerative heat treatment
  • welding
  • steam turbine
Accès libre

Modelling of Helicopter Main Rotor Aerodynamic Loads in Manoeuvres

Publié en ligne: 24 Apr 2020
Pages: 273 - 284

Résumé

Abstract

The article discusses the method of modelling of the helicopter main rotor aerodynamic loads during steady state flight and manoeuvres. The ability to determine these loads was created by taking into account the motion of each blade relative to the hinges and was a result of the applied method of aerodynamic loads calculating. The first part of the work discusses the basic relationships that were used to build the mathematical model of helicopter flight. The focus was also on the method of calculating of the aerodynamic forces generated by the rotor blades. The results of simulations dedicated to the “jump to hover” manoeuvre were discussed, showing the possibilities of analysing aerodynamic loads occurring in unsteady flights. The main rotor is considered separately in an “autonomous” way and treated as a source of averaged forces and moments transferred to the hub. The motion of individual blades is neglected, and their aerodynamic characteristics are radically simplified. The motion of individual blades is neglected, and their aerodynamic characteristics are radically simplified. This can lead to significant errors when attempting to model dynamic helicopter manoeuvres. The more complex model of helicopter dynamics is discussed.

Mots clés

  • helicopter
  • main rotor
  • aerodynamic loads
Accès libre

An Influence of Correction of the Ignition Advance Angle on the Combustion Process in SI Engine Fuelled by LPG with the Addition of DME

Publié en ligne: 24 Apr 2020
Pages: 285 - 292

Résumé

Abstract

The paper presents the results of tests of the SI engine fuelled by LPG with the addition of DME in the form of a mixture of gaseous fuels. Experimental tests were carried out on a chassis dynamometer in the full range of engine loads, at a fixed rotational speed: 2000, 2500 and 3000 rpm. The use of dimethyl ether (DME) as a fuel component makes it possible to exploit its important advantages. DME can be produced as a renewable fuel, which is important from the point of view of ecology. Another important fact is the presence of oxygen in this fuel, which has a positive effect on the engine volumetric efficiency. During the tests, the ignition timing was also adjusted due to the very good DME flammability. Two additional correction levels were applied, increasing the ignition advance by 3 and 6 CA degrees, compared to the factory settings of the driver. The analysis of the obtained results allowed determining the dependence of the basic engine parameters, in the function of the correction of ignition advance angle. In the summary, attention was also paid to the possibility of determining corrected maps of the ignition advance angle taking into account the variable proportions of fuel components.

Mots clés

  • Dimethyl ether
  • DME+LPG
  • fuel blend
  • SI engine

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