No 3 (2020)

Articles

Methodology for conducting climatic tests in cabins and habitable compartments of wheeled and tracked vehicles

Vereshchagin S.B.

Abstract

In the course of many years of climate research and analysis of research works by other authors, a number of methodological errors were identified that did not allow obtaining objective and reliable research results in some cases. As a result of evaluating a number of research materials of domestic and foreign researchers, it was revealed that the real temperature and humidity characteristics are hidden inside the habitable compartments. This was done, most likely due to a commercial interest in distorted research results. Since the beginning of the 90s of the twentieth century, the author often had to take part in works of improving the climatic characteristics inside the inhabited compartments of special wheeled and tracked vehicles, but the vehicles were completely unsuitable for installing climate control systems by their design and did not have free power to ensure their mechanical and electrical drive. It is especially difficult to provide the required climatic characteristics in the habitable compartments at high temperatures. This is due to the fact that the cost of cold in the habitable compartment is 5-7 times higher than the cost of heat, besides, the units used to generate cold require greater precision and quality of manufacture compared to other units, and large vibration and shock loads lead to damage system parts and assemblies and refrigerant leaks. The studies were carried out to objectively assess the heat fluxes entering the cabins and habitable compartments. The results were compared with previous methodological developments. In the process of research it was determined that the main heat load of the cabins and habitable compartments is borne by solar radiation, penetrating into the habitable compartment through transparent fences. The recommendations for climatic testing of full-size vehicles and cabin prototypes based on the results of field studies were given. Full-scale climatic tests are inherently the most difficult, since they depend on changeable weather, and in many cases cannot be objectively reproduced in a climatic chamber.
Izvestiya MGTU MAMI. 2020;(3):2-6
pages 2-6 views

Comparative characteristics of diesel engines and gas turbine power plants for mobile vehicles

Gusarov V.A., Godzhaev Z.A.

Abstract

The paper considers the use of diesel-electric power plants on mobile vehicles, analyzes their use and application. Comparative power and mass characteristics of diesel and gas turbine power units are given; the positive and negative aspects of their use are shown. The efficiency of the introduction of gas turbine engines on tractors of various traction classes for agricultural purposes has been determined and a new kinematic diagram of the power plant of a mobile vehicle has been developed. An analysis was carried out and it was established that gas turbine agricultural equipment was never produced in Russia. There were carried out the individual experimental studies of not of a systemic nature, which were terminated for reasons independent of the result. The aim of the work is to develop an innovative kinematic diagram with an electric drive and a power unit based on a gas turbine engine for a mobile agricultural vehicle, using the latest advances in science and technology in terms of the development of gas turbine technologies. It has been established that the mass-energy characteristics of gas turbine plants are much better than diesel ones: the level of vibration is significantly lower, the torque of the power plant at low speeds is higher, the operation of the tractor is simpler. All these open up wide prospects for their use on mobile agricultural vehicles. Experimental studies on the processing of 1 hectare of area in terms of economic efficiency have shown the indisputable advantage of an almost laboratory model of a tractor with a gas turbine engine, relative to the same tractor with a diesel engine, which has been produced for many years, expressed, despite a slightly higher fuel consumption, in the use of cheaper kerosene.
Izvestiya MGTU MAMI. 2020;(3):7-13
pages 7-13 views

Problems of using active-recuperative suspension and ways to solve them

Zamyslov V.M., Yesakov A.E.

Abstract

The aim of the work is to reveal the unobvious disadvantages of active-recuperative suspension, as well as to identify possible options for dealing with them. Such problems are the danger of suspension breakdown in the active mode, the impossibility of operating in the regenerative mode when the suspension deformation rate is below the threshold, and the system operation in swing mode. The novelty of the work lies in the fact that these aspects of the functioning of the active-recuperative suspension system were not previously considered. The problem of the increased risk of suspension breakdown is that in the active mode, the deformation of the elastic device occurs not only due to the work of external disturbance (road irregularities), but also due to the work performed by the actuator. The following solutions are offered: correct selection of system parameters; collection of additional information about the roughness profile; introduction of preventive measures into the control algorithm. The problem of the impossibility of operating in a regenerative mode at a suspension deformation rate below the threshold is that the electromotive force of induction on the rotor winding at low speeds may be lower than the threshold charging voltage at the terminals of the energy storage device. The following solutions are offered: dry friction in the suspension; introduction of a shock absorber with a pronounced degressive characteristic into the suspension structure; lowering the charging threshold voltage by separating the supply and charging circuits using a voltage converter; introduction of a “scattering chain” into the armature chain; optimal control of the excitation circuit. The problem of the system operation in the swing mode is that, under certain conditions, energy is supplied to the oscillatory system through the actuator, resulting in a gradual increase in the oscillation amplitude. The following solutions are proposed: the introduction of an additional damper or regenerative connection on the deformation rate of the suspension.
Izvestiya MGTU MAMI. 2020;(3):14-22
pages 14-22 views

Mobility of aggregates of promising missile systems based on road trains with an active trailed link

Berdnikov A.A., Strel'tsov R.V., Dyunov V.A., Zol'nikov I.V.

Abstract

The aggregates of advanced missile systems (AAMS) include autonomous launchers of a mobile ground missile complex, transport-and-installation, refueling, maintenance and auxiliary technical means of technological equipment, which must have operational, tactical and strategic mobility. Operationaland tactical mobility is understood as the ability of the AAMS to move from one point to another in a certain time. Strategic mobility is characterized by the adaptability of the AAMS to its loading and transporting by other types of transport, including rail, air, water. The average speed of movement is taken as a measure of mobility, which should be developed by AAMS in order to ensure the timeliness, efficiency and safety of performing the assigned tasks, as well as the possibility of getting out of the influence of the damaging factors of a nuclear explosion, primarily from excess pressure in the front of the shock blast wave. It is possible to increase the mobility of the AAMS by locating it on the basis of road trains, however, the existing designs of aggregates of road trains have disadvantages that reduce the flotation and, as a result, the average speed of movement, these include low support and geometric flotation. The geometric flotation is influenced by design factors. For example, an increase in overall width is typical for a road train, as the trailing link under the influence of lateral reactions of the supporting surface relative to the tractor track is shifted towards the instantaneous turning center. This displacement causes an increase in resistance to movement on deformable soils, and, consequently, a deterioration in flotation and a decrease in a number of other operational properties of the road train. It is possible to increase the mobility of the AAMS by placing them on the basis of a road train with an active trailed link, controlling the distribution of power flows supplied to the wheels of an all-wheel drive road train depending on the possibility of realizing free traction by each wheel, changing the position of the road train center of inflexions depending on the steering wheel angle and maneuver.
Izvestiya MGTU MAMI. 2020;(3):23-28
pages 23-28 views

Entropy-statistical analysis of the air conditioning cycle of an aircraft

Merkulov V.I., Tishchenko I.V., Abalakin S.A.

Abstract

Most modern aircrafts widely use air conditioning systems in order to ensure comfortable flight conditions for passengers and crew, as well as to cool the equipment of the aircraft. The aircraft industry is developing every year and the requirements for such systems are growing. Preliminary calculations and analysis of such systems are of key importance in their development. Such calculations will help to determine the entire further path of system development and prevent many errors. They also help to regularly improve the performance of systems, in particular, their energy characteristics. The main requirements for systems are reliability, energy efficiency, and weight-and-dimensional characteristicss. The paper is devoted to analysis of the efficiency of the system and its individual units. In addition, there is considered separately the influence of third-party factors on the efficiency of the system, in particular, the presence of moisture in the working air flow. This article discusses the results of thermodynamic calculation and analysis by the entropy-statistical method of the air conditioning system in various operating modes. The efficiency of the system as a whole is considered and the influence of imperfection of each of its units in particular is analyzed. The standard parameters of the operation of such systems on airplanes were taken as the initial parameters for calculating the systems. For the analysis, a system with a two-wheel turbo-cooling unit with moisture removal on the high-pressure path was selected. A schematic diagram of the system is given, formulas for calculating the minimum required work to compensate the production of entropy for the units of the system are presented. To ensure the calculations, the software complexes MathCAD, Coolprop and Matlab were used.
Izvestiya MGTU MAMI. 2020;(3):29-35
pages 29-35 views

Increase of strength of cast-iron cylinder liners of engines of road construction vehicles

Ovsyannikov V.E., Shpitko G.N., Nekrasov R.Y., Vas'kov D.E.

Abstract

Cylinder liners made of gray cast iron are quite widespread in the design of engines of road construction vehicles. The negative properties of this structural material include relatively low strength and high fragility. This increases the probability of both manufacturing and operational defects. Therefore, improving the performance of the considered parts is an urgent problem. A promising direction in this case is the use of chemical-and-thermal treatment. The aim of the work is to study the effect of chemical-and-thermal treatment of gray cast iron on strength. The paper investigates the strength of cast iron subjected to chemical-and-thermal treatment (thermal diffusion surface alloying). On the basis of experimental studies, the effect of the thickness of the hardened layer on the strength was studied. A numerical model is created in the Ansys software. The effect of the hardened layer on the strength of cylinder liners of engines of road-building vehicles is investigated.
Izvestiya MGTU MAMI. 2020;(3):36-40
pages 36-40 views

Optimization of the ethanol-fuel emulsion composition for use in diesel engines

Plotnikov S.A., Kartashevich A.N., Plyago A.V., Pachurin G.V.

Abstract

The use of alternative fuels of biological origin, in particular, alcohols, should be considered as a matter for the very near future. Scientists around the world are exploring more and more concentrated compositions of ethanol-fuel emulsions with various additives. However, to date, the reasonable limits of substitution of diesel fuel with ethanol have not been determined. Taking into account the depth of the problem, first of all, it is necessary to consider the creation of ethanol-fuel emulsions with a number of necessary properties, which is possible only if additives are used. The analysis of the additives used in the fuel showed that the directional effect of the additives is usually very narrow. Accordingly, a complex action additive is required to ensure a number of necessary properties of ethanol-fuel emulsions. The tests were carried out in several stages. The stability of the new fuel composition was investigated using various additives. The additive with the best performance was determined and adopted for further use in experiments. Further, the comparative tests of the operation of the fuel supply equipment, both on the basic fuel and on new fuel compositions, were carried out. The final stage of the research was to check the parameters of the engine operability as a whole when working at the main load and speed modes. The article considers a possible variant of the action of a complex additive based on molybdenum disulfide MoS2 as a combustion ignibitor. A hypothetical type and mechanism of reactions occurring in the combustion chamber of a diesel engine is presented. The results of experiments on the performance of injectors 455.1112010-50 on various compositions of new fuels and under changing conditions are shown. Environmental performance indicators of the 4ChN 11.0 / 12.5 engine are considered when operating according to the external speed characteristic on various fuel compositions. Based on the results of the data analysis, conclusions were drawn about the limitation of the presence of ethanol in the mixture and the substitution limit for the main fuel was justified.
Izvestiya MGTU MAMI. 2020;(3):41-47
pages 41-47 views

Overview of approaches to driver fatigue recognition and existing technical solutions

Saprykin Y.D., Ryazantsev V.I., Smirnov A.A.

Abstract

The article analyzes the existing methods for determining the driver's condition. Driving in a state of fatigue, according to various statistics, is the cause of a large number of road traffic accidents (RTA). The percentage of accidents in Russia associated with the driver falling asleep while driving in 2018 is about 20%, in the USA the number of accidents for the same reason reaches 100,000 per year. The aim of the work is to review existing approaches to recognizing driver fatigue and existing technical solutions in this area. The article discusses such approaches as fatigue recognition based on the physiological state of the driver, recognition based on the driver's behavior, namely his speech and visual signs while driving, fatigue determination based on the nature of the vehicle's movement on the road and based on the driver's actions on the controls, the approaches based on the subjective assessment of the driver's condition. The advantages and disadvantages of each of the approaches were analyzed. The paper also provides an overview of existing fatigue recognition systems from various manufacturers that are currently used on vehicles and are designed to warn the driver of impending fatigue. It was revealed that in modern conditions of road transport operation, the most optimal approaches to fatigue recognition are based on an assessment of the driver's impact on the steering wheel, visual signs of driver fatigue and the nature of the vehicle's movement on the road, therefore, it is proposed to further focus on these methods.
Izvestiya MGTU MAMI. 2020;(3):48-58
pages 48-58 views

Experimental evaluation of the load capacity of the rollers of gravity conveyors for pallets

Safronov Y.V., Nosko A.L.

Abstract

The main approaches to calculating the load capacity of the carrying rollers of gravity conveyors are presented. It is shown that in practice, in the designs of modern non-driven conveyors for pallets, the priority when choosing the pitch of the carrier rollers is the stability of the movement of the load, rather than minimizing the number of rollers. In connection with the urgent task of reducing the metal consumption and the cost of gravity roller conveyors for pallets, the purpose of the work is to experimentally determine the load capacity of the rollers of gravity conveyors for pallets with plastic bearing housings. The experimental studies were carried out in the laboratory of the Department of Applied Mechanics on a Galdabini Quasar 50 universal testing machine using a special roller support for two roller designs - with a solid axis and on half-axles. The test results showed that the stiffness of a roller with a solid axis in the load range up to 670 N is about 1358.4 N / mm, and in the load range from 670 to 1500 N - 2229.9 N / mm. The rigidity of the roller on the axle shafts in the entire load range is 2048.0 N / mm. The analysis of the obtained results showed that for loads over 670N the use of the axle slightly increases the stiffness coefficient, and, on the contrary, it decreases in the load range up to 670N. In order to reduce the cost of carrying rollers with plastic bearing housings, it is advisable to use a design on semi-axles.
Izvestiya MGTU MAMI. 2020;(3):59-64
pages 59-64 views

Simulation of vehicle tires based on the finite element method

Tomashevskiy S.B.

Abstract

Modeling of wheeled vehicles is one of the main directions of development and practical application of software systems based on modeling the dynamics of body systems. In this paper, a technique for analyzing a vehicle tire by the finite element method under various types of loading is considered in order to identify the parameters of its simplified dynamic models. Based on the finite element method, a refined tire model is created. It takes into account the complex geometric shape of various tire parts, their material properties, as well as the contact interaction of the tire with the support. The efficiency of this model was tested, both when performing static calculations of the stress-strain state of the tire from the action of an external load, and when solving the generalized eigenvalue problem. The great influence of external load on the natural frequencies and vibration modes of the tire is confirmed. One of the possible applications of the considered method of finite element modeling of a tire is the performance of refined calculations of the dynamics of wheeled vehicles in the “Universal Mechanism” software package. There are several variants of dynamic tire models that can be used to study the dynamics of off-road wheeled vehicles, including a model based on the method of discrete elements and a model based on the method of coupled substructures. A model based on the method of discrete elements represents a number of absolutely solid bodies-particles, connected to each other and by a wheel disk by a set of elastic-dissipative elements. Each particle of this model has three linear degrees of freedom relative to the wheel disk. The results of calculations of the refined finite element model of the tire are necessary to identify the mass and elastic-dissipative properties of this dynamic tire model. In the model based on the method of connected substructures, the elastic displacements of the tire are represented as the sum of the admissible shapes of the elastic body. Static and natural vibration modes are used as permissible forms of an elastic body, calculated using a refined finite element model of the tire.
Izvestiya MGTU MAMI. 2020;(3):65-74
pages 65-74 views

Mathematical modeling of the functioning process of a single-cylinder air-cooled diesel engine taking into account the consumption of crankcase gases

Pavlov D.V., Platonov K.Y., Khmelev R.N.

Abstract

At present, the most effective method for studying internal combustion engines (ICE) is mathematical modeling and computational experiment. The use of a computational experiment can significantly reduce material and time costs in the research, design and refinement of the internal combustion engine. At the same time, despite the high level of the applied mathematical models, there are practically no studies aimed at establishing the regularities of the influence of the state of the cylinder-piston group (CPG) on the crankcase gas consumption and other indicators of engine operation at steady-state and transient modes. This article is devoted to solving an urgent problem associated with the development of a theoretical base that provides a comprehensive simulation of steady-state and transient modes of diesel engine operation, taking into account the consumption of crankcase gases. The article presents a mathematical model of a diesel engine based on thermal mechanics, which reflects the main features of the engine as a system that converts energy in time. The system of equations of the mathematical model is based on the laws of conservation of energy, mass, equations of motion of solid links and includes differential equations for the rates of change in the temperature and density of the working fluid in the cylinder and in the crankcase of the internal combustion engine, the ideal gas equation of state, as well as differential equations for the change in the angular speed and angle of motor shaft rotation. The mathematical model is tested on the example of a small-sized single-cylinder diesel engine 1Ch9.5 / 8.0 with air cooling. This type of engine is widely used for small-scale mechanization in agriculture, generator sets, etc. The article presents the results of calculations of a number of engine operating modes in comparison with the results of field tests carried out at the test bench.
Izvestiya MGTU MAMI. 2020;(3):75-82
pages 75-82 views

Technical and economic analysis of the efficiency of a low-power wind farm in the climatic conditions of the center of the European part of Russia

Jinov A.A., Shevelev D.V., Metlitsky N.E.

Abstract

Nowadays, the world is actively developing alternative energy based on solar energy and wind energy. The reason for this is the obvious signs of global warming, probably caused by the emissions of greenhouse gases - products of combustion of fossil fuels. The production of electrical energy at solar and wind power plants, unlike traditional thermal power plants, does not lead to the emission of greenhouse gases into the atmosphere. This article examines the potential of wind power plants in the central zone of the European part of Russia, using the example of the Kaluga region. The open climatic data METAR of the meteorological station of the Kaluga International Aerodrome named after Konstantin E. Tsiolkovsky (KLF) was used when writing the paper. Authors used data on the average wind speed for three-hour intervals over one year. An analysis of the wind speed was carried out and a graph of the probability of observing one or another wind speed was built. The graph showed that the average wind speed in the Kaluga region is about 2 ... 4 m / s. The calculation of the generation of electrical energy by a serial low-power wind generator was made, the coefficient of utilization of the installed capacity of the ICUM = 7% was determined. It has been established that the Kaluga region has a low wind energy potential. It is possible to obtain electricity from wind in the Kaluga Region, but calculations shown that the payback period for such power plants under these conditions, even without taking into account the costs of installation, auxiliary equipment and maintenance of the wind generator, is about 30 years. As a result of the study, it was concluded that there is no economic feasibility of operating low-power wind power plants in the central zone of the European part of Russia.
Izvestiya MGTU MAMI. 2020;(3):83-87
pages 83-87 views

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