Transportation Diesel Engine Research Articles

The influence of the design features of the fuel injector atomizer on the process of diesel fuel injection

Abstract. Problem. Increasing the demands for the technical and economic characteristics and the resource of modern augmented diesel engines requires finding ways and approaches to improve their design and systems, in particular, their fuel supply system. Changing the design parameters of the fuel injector atomizer allows to influence the conditions of fuel injection, its atomization in the combustion chamber, and the efficiency of the engine. The number and mutual arrangement of the nozzle holes of the fuel injector atomizer and their diameter are chosen by manufacturers based on the design features of the engine, in particular, the configuration of the combustion chamber and the conditions for filling the cylinder with fresh air. Goal. The purpose of the work was to carry out comparative numerical modelling to assess the influence of the number and diameter of the nozzle holes of the fuel injector atomizer on the diesel fuel injection process. Methodology. The problem is considered in a three-dimensional non-stationary setting. For numerical modelling, the geometry of the flow part of the fuel injector atomizer was formed, taking into account its design features (standard and modernized versions). The standard version has 7 nozzle holes with a diameter of 0.25 mm (evenly arranged relative to the axis of the atomizer, and the modernized version has 4 holes with a diameter of 0.3 mm in the standard place, evenly arranged relative to the axis of the atomizer and, additionally, 4 holes with a diameter of 0.2 mm from above (in the area of the closing cone) evenly arranged relative to the axis of the atomizer, but with a rotation around the axis of the atomizer by 45 degrees relative to the lower holes. To describe the process of the diesel fuel flow in the flow part of the fuel injector atomizer, the k - ε turbulence model is used, and to describe the process of phase transition from a liquid state to a vapour state – a mixture model is used. Results. The obtained results showed that the use of two rows of nozzle holes of different diameters for the atomizer of the fuel injector of the transport diesel engine allows to effectively organize the fuel injection process. For the atomizer nozzle of the modernized design, the volumetric fuel consumption is 30% for the upper holes and 70% for the lower ones. Originality. The scientific novelty of the work lies in determining the influence of the number and diameter of the nozzle holes of the fuel injector nozzle on the conditions of diesel fuel injection, taking into account cavitation effects. Practical value. The total area of the nozzle holes in the modernized version was increased by 20%, which makes it possible to increase the cycle supply of diesel fuel. It is especially important when using new types of fuel with a lower paraffin content and, accordingly, lower caloric content

Influence of multiphase fuel injection on the technical and economic indicators of a transportation diesel engine

Influence of multiphase fuel injection on the technical and economic indicators of a transportation diesel engine

Thermodynamic condition of cylinder diesel group for infrastructure objects under high temperatures

The article presents the results of research on the influence of ambient temperature on the thermal state of cylinder-piston groups of diesel engines, carried out by the experimental-calculation method on diesel engines 12ChN 18/20 (M787B) and 8ChN 13/14 (YAMZ-7511.10) of autonomous sources on factory test benches. In the experimental study of the effect of temperature change on the thermal state of cylinder-piston groups, the diesels were equipped with a special water-air heat exchanger for heating the air at the suction to the compressor, and the temperature of the suction air was regulated by changing the flow rate of hot water through the water-air heat exchanger. In the experimental study, along with the thermometry of parts of cylinder-piston groups, the engine operating process was indicated, the heat balance was taken, etc.; and the experimental data of other researchers were analyzed. The results of this experimental study, as well as analyzing the results of earlier work on the effect of temperature on the thermal state of cylinder-piston groups allowed to obtain empirical dependencies of local temperatures of the walls of their parts, the distinguishing feature of which is that as variables are considered their relative (dimensionless) values, which increases the degree of experimental data. The results of the performed research can be used for the calculated estimation of the temperature level in the walls of parts of cylinder-piston groups of diesel engines of a wide class of both stationary and transport diesel engines, while providing satisfactory convergence of the calculation results with the experimental data.

Regulation of the fuel injection advance angle in a transport diesel engine

The toxicity indicators of exhaust gases of a diesel engine largely depend on the quality of the fuel supply process. The possibility of a significant improvement in the toxicity of the exhaust gases of a diesel engine by optimizing the phase of the start of fuel supply - the fuel injection advance angle is shown. To assess the influence of the fuel injection advance angle on the dynamic performance of the engine and the toxicity of exhaust gases, a mathematical model of the engine has been developed. The model contains differential equations for the main elements of the combined engine - its piston part, turbocharger, in take and exhaust pipelines. These equations include polynomial dependences of the main engine parameters on its operating parameters. The object of research was diesel type D-245 (4 ChN 11/12.5) produced by the Minsk Motor Plant. Calculations of the acceleration of the engine with a variable fuel injection advance angle have been carried out. The influence of the law of regulation of the advance angle of fuel injection on the duration of the transient process and emissions of normalized toxic components is determined.

To the substantiation of charge air parameters on different operating modes of diesel engines of diesel locomotives

A numerical method is proposed for quantitative assessment of the specific effective air consumption and the influence of atmospheric air temperature on the working process of a diesel engine, taking into account various modes of its operation. The dynamics of changes in the values of the coefficients of excess air and filling the cylinder with a fresh air charge over the period of the diesel operating process is substantiated depending on the temperature of the outside and charge air, as well as the position of the locomotive driver’s controller, obtained in the form of tabular data and graphical dependencies. The possibilities of increasing the fuel efficiency of operating diesel engines up to 5 - 10 percent through quantitative and qualitative regulation of coolant temperatures or through throttling, heating and cooling of charge air are formulated. It is recommended to continue research to improve the quality of the operating process of supercharged transport diesel engines by substantiating the air characteristics of such diesel engines and their subsequent combination with diesel locomotive and fuel characteristics under partial load conditions and, especially, at low ambient temperatures.

IMPROVING THE ACCURACY OF SYSTEMS FOR GRAVIMETRIC CONTROL OF PARTICULATE MATTER IN EXHAUST GASES OF TRANSPORT DIESEL ENGINES

The requirements of regulatory documents - UNECE Regulations R-49, R-96, international standard ISO 8178, etc. were analyzed regarding the technical characteristics and conditions of use of reference full-flow and alternative partial-flow systems (tunnels) for diluting the exhaust gases of transport diesel engines with air and carrying out gravimetric control of the content of solid particles in them. The world and domestic experience of operating dilution tunnels of various types - full-flow with 1st and 2nd dilution lines and partial-flow mini- and micro-tunnels and partial-flow mini- and micro-tunnels were studied, which made it possible to establish empirical dependencies for evaluating the degree of influence of the temperature regimes of gas sampling on the accuracy of measurements of mass emissions particulate matter in different modes of diesel operation. Mathematical models have been developed to determine the sample temperatures of diluted exhaust gases in tunnels of various types and to estimate the resulting measurement error of the normalized average operational emission of diesel particulate matter - the PM indicator. Based on the results of environmental tests of transport diesel engines 1Ch12/14 and 4ChN12/14 according to the 13-step ESC test cycle and developed mathematical models, calculation studies were carried out to assess the effect on the accuracy of a mini-tunnel with a diameter of 10 cm and a micro-tunnel with a diameter of 3 cm of the sampling temperature regimes, which were compared with a reference tunnel with a diameter of 46 cm. The research results proved the expediency of adjusting the temperature of the sample in the micro-tunnel to increase its accuracy by eliminating the significant methodical errors of measuring the PM indicator, which amount to -1.6 ... -1.7%. It was established that in the mini-tunnel the corresponding errors are not significant and amount to -0.3 ... -0.4%, which indicates that there is no need to adjust the temperature of the sample in this system.

RESEARCH OF A HIGH-EFFICIENCY CHARGE AIR COOLER

Currently, internal combustion engines have become widespread as sources of mechanical energy in many areas of human activity. It is the internal combustion engines that were and remain the most widespread in transport, where, as a rule, strict requirements are put forward for the mass-dimensional characteristics of the engines and the power plant as a whole. In order to meet these requirements, there is a constant increase in the level of forcing of the engines. For diesel engines, the most common technical measure that provides an increase in the level of engine forcing with almost unchanged weight and dimensional characteristics is an increase in supercharging pressure. However, as a result of air compression, its temperature increases, which is proportional to the degree of increase in air pressure in the compressor. An increase in air temperature causes a decrease in the mass charge of the cylinders, and therefore, a significant deterioration in the fuel combustion process. It also causes an increase in the level of maximum temperatures of the cycle, which in turn causes an increase in thermal loads and the rate of formation of nitrogen oxides in diesel cylinders. The above determines the urgency of the tasks of implementing effective charge air coolers in modern high-pressure transport diesel engines. This technical problem can be solved using air or liquid coolers. The article considers a liquid cooler, because compared to an air cooler, it can be made more compact, allows to achieve a much smaller length and volume of the intake tract, as well as to simplify the layout of the intake tract as part of the power plant as a whole, which is a priority for diesel engines. The article considers the influence of the design parameters of the supercharged air cooler on its overall characteristics and the hydraulic resistance of the supercharged air flowing through the cooler. Thus, the article provides data indicating the possibility of making a compact, highly efficient supercharged air cooler while maintaining its hydraulic resistance at an acceptable level by choosing rational parameters.

IMPROVMENT OF ENVIRONMENTAL PERFORMANCE TWO-STROKE DIESEL DURING OPERATION

The development of world shipping is taking place in the context of ever-increasing requirements to reduce the concentrations of toxic components of gaseous combustion products of hydrocarbon fuels. Concentration limits for these substances are regulated in accordance with Appendix VI of the MARPOL 73/78 Convention. Among the controlled components of diesel exhaust gases, nitrogen oxides are the most dangerous for humans and environment. However, a decrease in the content of nitrogen oxides is inevitably associated with limitations on the maximum cycle temperature, that is, thermal efficiency, and hence with a deterioration in the fuel efficiency of the engine. At the moment, in order to reduce emissions of nitrogen oxides by large transport diesel engines, the most widely used is the recirculation of exhaust gases into the air receiver. A significant disadvantage of using this scheme is the need for cooling the exhaust gases and their additional purification, which leads to an increase in the weight and size characteristics of the system and to its rise in price. Therefore, to reduce its cost, it seems logical to combine exhaust gas recirculation with other ways to reduce nitrogen oxide emissions. For engines in operation, one of these methods is to change the angle of fuel injection. It can be assumed that the later the fuel is injected into the cylinder, the lower the temperature of the air charge will be and, accordingly, the lower the maximum combustion temperature, and hence the amount of nitrogen oxides. The calculation of nitrogen oxide emissions was simulated for the main engine MAN-B&W 7S50MC-C installed on the vessel "LILA SHANGHAI". Initially, the model created using the AVL-BOOST package was verified based on the available indexing results. After verification, the calculation of emissions of nitrogen oxides NOx was made with a variation in the angle of the start of fuel combustion at the nominal mode. The composition of the gases in the receiver was taken unchanged. As the fuel combustion start angle shifted further from the TDC, deterioration in fuel efficiency and a drop in cylinder power were observed, while reducing the mass of emitted nitrogen oxides NOx. However, it can be said that the environmental friendliness of an engine improves much faster than its fuel and power characteristics deteriorate. The above calculations show that for engines already in operation, changing the fuel injection angle makes it possible to reduce nitrogen oxide emissions. Therefore, this approach can be combined without much difficulty with other methods, thus reducing the cost of environmental improvement of the engine.

Methods for estimating the durability of the needle bearing of the piston head of the connecting rod of a transportation diesel

The article presents the results of an experimental study and analytical evaluation calculations to check service life and increase durability of the needle bearing of piston head of connecting rod of a transport diesel engine. The primary reasons for the violation of the nominal operation of the main units of this mechanism have been established. Corresponding recommendations are proposed for carrying out accelerated tests for durability, reducing the thermal loads of the bearing operation and, as a consequence, improving the quality and service life of its entire piston group. Theoretical and experimental methods for determining the nominal life of the needle bearing of the piston head of the connecting rod (PHCR) of a transport diesel engine are proposed. The theoretical methodology allows obtaining reliable values of durability, taking into account the distribution of the working load over the rolling elements, as well as the mobility of the piston pin and sleeve. The performed calculations make it possible to correct and clarify the standard mathematical model for determining the nominal life of the PHCR needle bearing, depending on the distribution of loads on the rolling elements (rollers) under different operating conditions. This experimental technique with an acceleration factor of 10 is based on a twofold increase in the force effect on the elements of the PHCR needle bearing. This was achieved by assembling the bearing using a special technology, which is described in detail in the work. A significant decrease in the thermal effect and a decrease in radial loads on working rollers have been established. For ensure the regular oil supply into bearing during engine operation, a technique was developed to increase the load on the roller in contact zone, which significantly influenced durability and made it possible to conduct accelerated tests with a reliable yield. Its results of operational research and experience in design work correlate and are sufficiently explained by the developed methods, which allows them to be used for the improvement and modernization of connecting rods with needle bearings in PHCR. That is a permission to use these methodic for doing perfect and modern the needle bearing of the connecting-rod piston.
 Keywords: diesel, test procedure, needle bearing, rollers, piston head of the connecting rod, durability.

Результаты испытаний водно-топливной микро-эмульсии с добавкой мазута на дизеле транспортного назначения

Results of a comparative experiment on a transport diesel engine of the effect of a water-fuel micro-emulsion with the addition of 15%, by weight, of IFO-180 fuel oil on the consumption of fuel, CO2, CO, CH, NOx when operating at the maximum torque mode.

Результаты испытаний водно-топливной микро-эмульсии с добавкой мазута на дизеле транспортного назначения

Results of a comparative experiment on a transport diesel engine of the effect of a water-fuel micro-emulsion with the addition of 15%, by weight, of IFO-180 fuel oil on the consumption of fuel, CO2, CO, CH, NOx when operating at the maximum torque mode.

Тепловое и напряженно- деформированное состояние чугунной крышки цилиндра

Based on the FEM calculation, the choice of cast iron with vermicular graphite for the cast cylinder head of a transport diesel engine when it is converted into a ship's one is justified.

Di-ethyl ether-diesel blends fuelled off-road tractor engine: Part-II: Unregulated and particulate emission characteristics

The use of oxygenated fuels, including ethanol, methanol, diethyl ether (DEE), and dimethyl ether (DME) in CI engines has emerged as an effective way to reduce CO, HC, and PM emissions. DEE, in particular, has significant potential to be used in CI engines. Unlike DME, it exists as a liquid state at room temperature and pressure, making its handling very smooth. In this experimental study, DEE-diesel blends were used to power an off-road tractor engine. Previous studies investigated the performance and regulated emission characteristics of DEE-fueled vehicles/ engines; unregulated emissions and particulate characteristics were not studied thoroughly. This study, therefore, investigates the effect of DEE-diesel blends on unregulated and particulate emissions from the engine. Unregulated pollutants investigated in this study include individual oxides of nitrogen (NO, NOx, NO2), saturated and unsaturated hydrocarbons (n-pentane (n-C5H12), n-octane (n-C8H18), iso-butene (iso-C4H8)), and organic and inorganic species (Sulphur dioxide (SO2), formic acid (HCOOH) and formaldehyde (HCHO)). Particulate emission characteristics include total particle mass (TPM), total particle number (TPN), particulate mass-size distributions, and count mean diameter (CMD). Four test fuels were used in this study namely: DEE0, DEE15, DEE30 and DEE45 (0%, 15%, 30% and 45% DEE (v/v) blended with mineral diesel). The results from DEE-diesel blends were compared with baseline mineral diesel (DEE0). The experiments were conducted at a constant engine speed of 1500 rpm at varying engine loads. At all engine operating conditions, DEE-diesel blends resulted in significantly lower TPN compared to baseline mineral diesel. A similar trend was observed for TPM; however, DEE15 showed slightly higher TPM than baseline mineral diesel. Emissions of individual oxides of nitrogen were also relatively lower than baseline mineral diesel. The addition of DEE in mineral diesel exhibited a slight increase in unregulated emission species concentrations such as formaldehyde, formic acid, sulfur dioxide, n-pentane, n-octane, iso-butene. However, the absolute concentration levels were still quite low. This study concluded that DEE could potentially displace mineral diesel partially, without any changes in fuel injection equipment, and achieve an improvement in PM-NOx trade-off in off-road transport diesel engines.

Engine durability and lubricating oil tribology study of a biodiesel fuelled common rail direct injection medium-duty transportation diesel engine

Biodiesel has emerged as a viable alternative to mineral diesel in the transport sector to replace fossil fuels partially. However, long-term compatibility with engine hardware must be evaluated to ensure a smooth transition. Long-term material compatibility studies of Karanja oil methyl ester (biodiesel) blends with the hardware of a modern common rail direct injection system equipped diesel engine used in sports utility vehicles have been carried out in this investigation. A long-term endurance test was carried out in two phases, each lasting 274 h and utilizing (i) baseline mineral diesel and (ii) a 20% v/v Karanja biodiesel blended with mineral diesel (KB20). After completing the first phase, the engine was dismantled, and essential engine components were investigated for carbon deposits and physical wear using several techniques. Before proceeding with the next phase of the endurance test KB20, new engine components were installed in the engine, and then the test was executed. The KB20-fuelled engine exhibited lower wear on the valves and crankpins but higher wear of liners, piston rings, pistons, gudgeon pin, small and big end bearings of the connecting rod, and the main bearings. Fuel chemistry affected the lubricating oil efficacy and its residual useful life. Lubricating oil from the KB20-fuelled engine exhibited a higher increase in density and ash content. KB20 fuelled engine's lubricating oil underwent higher oxidation and polymerization. The surface roughness characteristics of the cylinder liner were measured before and after the endurance test for comparative wear evaluation during both phases of the endurance test. Carbon deposits on the cylinder head, piston top, and injectors were compared, and the pistons of the KB20 fuelled engine exhibited higher carbonaceous deposits. Biodiesel blends harmed the CRDI engine's fuel injection system. Biodiesel harms the fuel injection equipment (FIE) of the CRDI engine. Various tribological tests were performed on the lubricating oil samples collected regularly to examine the compatibility of KB20 vis-à-vis mineral diesel. This series of tribological tests on the lubricating oil samples assessed the effect of fuel chemistry on the lubricating oil's performance and residual useful life. Tests included variations in lubricant density, viscosity, flash point temperature, moisture content, pentane and toluene insoluble, and copper corrosion with time. The study summarily concluded that Biodiesel blends could be utilized in a CRDI engine without causing major engine durability or lubricating oil degradation issues.

DEVELOPMENT OF MICROPROCESSOR SYSTEMS CONTROL OF GAS ICE FOR OPERATION WITH LIQUEFIED PETROLEUM GAS

The expediency of converting the transport diesel engines in operation into gas internal combustion engines with spark ignition for operation on liquefied petroleum gas has been substantiated. It is shown that the use of liquefied petroleum gas instead of diesel fuel can reduce the operating costs of vehicles. Multifunctional electronic microprocessor control systems based on Avenir Gaz 37 level “A” and Avenir Gaz 37 level “B” electronic control units have been developed. It is shown that an electronic microprocessor control system with an Avenir Gaz 37 electronic control unit of level "A" allows converting diesel engines into gas internal combustion engines with LPG supply through a gas-air mixer into the intake manifold. The test results showed the high energy and efficient performance of the gas internal combustion engine. The second electronic microprocessor control system with an electronic control unit Avenir Gaz 37 of level "B" allows converting diesel engines into gas internal combustion engines with LPG injection through an accumulative power supply subsystem and multipoint injection of liquefied petroleum gas (Common Rail type) in combination with the use of a contactless electronic subsystem ignition with a movable voltage distributor and a cylinder filling control subsystem with a charge of the working mixture. At the same time, Avenir Gaz 37 "B" ECU with a loaded B1 level software module provides group injection of LPG into the intake manifold and sequential injection with a B2 level software module. The principle of operation of each of the three subsystems, which the D-240-LPG-"B" gas engine is equipped with, is described. The tests carried out on the D-240-LPG-"B" gas engine with the Avenir Gaz 37 "B" control unit confirmed its operability.

SCIENTIFIC PRINCIPLES OF INCREASING THE EFFICIENT PERFORMANCE OF DIESELS WHEN USING BIOFUELS

The use of biological fuels based on vegetable oils and other similar raw materials in diesel engines in developed countries can reduce the cost of mineral diesel fuel and improve the environment. This issue is relevant for Ukraine as well, in connection with which the governing bodies pay great attention to it. The deepening of knowledge in the study of the peculiarities of the flow of operating cycles of diesel engines, their power and toxic characteristics at the same time contributes to the optimization of the use of these types of fuel. In this work, the main issues related to the use of vegetable oils, such as sunflower, rapeseed, corn oils and their ethyl esters, both in pure form and in a mixture with mineral diesel fuel, are considered as a biological component of fuel. Theoretical issues and experimental data related to the use of these fuels in diesel engines are considered. Experimental studies were carried out on diesel engines D21A and four-cylinder - Skoda - an analogue of the 1.9-liter Volkswagen engine with turbocharging. Economic and toxic characteristics were obtained by load and speed characteristics. There is an increase in the consumption of mixed fuel in comparison with mineral fuel, the toxic characteristics were better in some indicators, in some cases, for example, when operating at increased capacities, they worsened relative to those when operating on mineral fuel. The basic principles of the effective use of biofuels in transport diesel engines are formulated in terms of energy and toxic indicators, as well as the corrosive effect of blended biofuels on fuel equipment. Today, gas stations in Ukraine only sell alternative fuels for gasoline engines. These are mixtures in various proportions of gasoline and bioethanol with a content of the latter up to 35–40% by volume. The price of such fuel is lower than the price of gasoline. Biodiesel fuels are not commercially available, although they would also cost less than mineral diesel fuel. It is likely that the use of biodiesel fuels is restrained due to the need to adapt the diesel engine to these fuels and to monitor the state of the fuel equipment. However, these costs are small and can be easily compensated for by the difference in the price of mineral and biodiesel fuels. It can be assumed that, first of all, biodiesel will be introduced into agricultural machinery.

Two-phase mixture formation in transport diesel engine: the control algorithm and the devise for its implementation

The article reviews the issues dedicated to improving of energy and environmental indicators of automotive machinery by means of two-phase mixture formation in diesel engine. With this method, the 1st phase of mixture formation proceeds at intake stroke by the supply of the certain dose of fuel activator (gasoline, alcohol, biodiesel, etc.) into engine intake manifold, where a mixture of air and activator is formed. The 2nd phase proceeds at compression stroke by the supply of the major dose of diesel oil with the standard fuel supply system into combustion chamber. For the practical implementation of the described method, the diesel engine needs to be equipped with an automatic system for fumigation of air charge. The system contains electronic control unit (ECU), electromagnetic injectors, electric pump and sensors of engine speed and load mode. An algorithm of ECU operation for program control of injectors, supplying activator at the intake stroke, was developed. The sequence of actuation of injectors, coincident with the engine firing order, was substantiated. A formula for calculation of the duration of control pulse supplied to the injectors was derived. The proposed automatic system performs the activator injection, corresponding to the engine firing order, and the exact activator dosage, depending on engine speed and load mode, at the 1st phase of two-phase mixture formation.

DEVELOPMENT AND RESEARCH OF SYNTHESIS TECHNOLOGY CONVERSION OF VEHICLE DIESEL TO GAS ENGINES WITH SPARK IGNITION

The expediency of converting transport diesel engines into gas internal combustion engines with spark ignition has been substantiated. A multifunctional synthesis technology Avenir Gaz has been developed, designed to convert diesel engines of vehicles in operation into spark-ignited gas internal combustion engines operating on a cheaper and environmentally friendly gas fuel - LPG. The synthesis technology is based on three electronic microprocessor control units Avenir Gaz 37 of level "A", Avenir Gaz 37 of level "B" and Avenir Gaz 37 of level "C". It is shown that Avenir Gaz synthesis technology of level "A" allows converting diesel engines into gas internal combustion engines with LPG supply through a gas-air mixer into the intake pipeline, and level “B” provides group or sequential LPG injection by electromagnetic gas nozzles (common rail injection system ) into the intake manifold. Avenir Gaz synthesis technology of level "C" allows the use of an electronic inductive spark ignition system with an immovable voltage distributor (with two-spark or individual ignition coils).

Тепловая напряженность крышек цилиндров двигателей, конвертируемых в судовые

The article describes the characteristics of thermal loading of the cylinder covers of transport diesel engines during their conversion to marine diesels. The engines of the CHN14/14 type produced by the Yaroslavl Motor Plant are proposed as promising for use in marine power plants. A special feature of the engine design is the individual four-valve cylinder heads, which have a complex geometric shape. The conversion of automobile engines, the cylinder heads of which were made of aluminum alloys, to marine ones is accompanied by an increase in the degree of their acceleration. The cylinder heads in operation experience significant thermal and mechanical loads, which causes the need for increased requirements for the materials of the cylinder heads. The rational choice of the cylinder head material is one of the most important tasks to be solved when upgrading and boosting engines. Experience in the operation of marine diesel engines shows that in order to ensure the required reliability under prolonged exposure to elevated temperatures due to forcing, it is necessary to choose cast iron as a structural material. A three-dimensional model of the cylinder head is developed. When performing the calculations, the boundary conditions are justified, taking into account the local nature of the distribution of thermal and mechanical effects on the diesel cylinder head. As a result of numerical modeling, the stress-strain states of cylinder heads made of high-strength cast iron, ductile iron and cast iron with vermicular graphite are determined and analyzed. There has been proved the preference for using cast irons with vermicular graphite, which have satisfactory casting and physical and mechanical properties. The advantages of using cast iron with vermicular graphite include a decrease in the temperature of the cylinder head in the area of the inter-valve bridge. The possibility of increasing the engine power from 330 to 560 kW when replacing aluminum alloys with cast iron with vermicular graphite for the manufacture of cylinder heads is proved.

About the choice of parameters of the non-linear flexible coupling as damper in two-shaft transport diesel engines

The increase in power and speed of modern units with internal combustion engines (ICE) leads to the increase in dynamic loads in them. The effective means of dealing with dangerous torsional vibrations is the introduction of elastic couplings and damping devices, the characteristics of which are most often nonlinear. The features of existing approaches for the choice of their parameters are limited by the imperfection of the models of the devices themselves, the features of the models of machine units with internal combustion engines as multimass systems with several nonlinearities. Goal. The creation of the method for parameters synthesizing of an elastic coupling with a preload as a unit of limiting excessive vibrations in nonlinear models of machine units with twinshaft diesel engines. The following problems should be resolved: the dynamic synthesis problem is formulated as a nonlinear programming problem; a harmonic linearization method was developed for the equations of motion in integral form; the equivalent stiffness and average deformation of the nonlinear connection are determined; an algorithm for finding the vibration amplitudes of nonlinear connections has been created; a reliable nonlinear dynamic model of a machine unit with a 3TD diesel engine has been built; the results of computational studies are compared with experimental data. Methodology. The synthesis method is based on an efficient algorithm for solving analysis tasks. The equations of motion are written in the form of integral equations using the pulsefrequency characteristics of the linearized models. The main advantage of this approach for solving synthesis and optimization tasks is that the number of equations of motion is equal to the number of nonlinearities and the complexity of solving the analysis task is practically independent of the model’s number of degrees of freedom. The problem of dynamic synthesis of coupling parameters is formulated as a nonlinear program-ming task. Results. The parameters synthesis method for the elastic coupling with a preload as a means of limiting excessive vibrations in nonlinear models of machine units with twoshaft diesel engines has been developed. A method of harmonious linearization for the equations of motion in integral form, written using the pulsefrequency characteristics of linearized models, is presented. The task of dynamic synthesis of coupling parameters is formulated as a nonlinear programming task. Originality. The parameters synthesis task of the elastic coupling with a preload is solved as a task of nonlinear programming. An efficient algorithm for solving the analysis task is based on the method of harmonic linearization for the equations of motion in integral form, that are written using the pulsefrequency characteristics of the linearized models. Practical value. The reliable nonline-ar dynamic model of a machine unit with a twoshaft transport diesel engine 3TD has been built. The optimal parameters of the elastic coupling between the engine crankshafts have been determined. The results of computational studies are compared with experimental data.