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Vol 16, No 1 (2022)
- Year: 2022
- Articles: 11
- URL: https://journals.eco-vector.com/2074-0530/issue/view/5437
- DOI: https://doi.org/10.17816/2074-0530-2022.16.1
Heat engines
The choice of design parameters of main and conrod bearings for passenger car engines
Abstract
BACKGROUND: The creation of a new internal combustion engine begins with a preliminary design, during which the architectural design of the engine is born, the main features of its basic components are determined. Bearings (in this case, sliding bearings) are the cornerstones of the design, which create the foundation and form the basis – the skeleton of the power train mechanism and, as a result, the image of the future engine. Therefore, the exact selection of these key engine components is an ongoing challenge.
AIMS: Тo develop and propose an engineering method for selecting bearing parameters based on a statistical analysis of the most successful car engine designs implemented in practice.
METHODS: The method of comparative analysis of relative loads was used in the work, which allows to evaluate the loading conditions and the bearing capacity of main and conrod bearings using relative values familiar to engine engineers, such as the ratio of the diameters of the conrod and main journals to the cylinder diameter (d/Dc, d1/Dc), the ratio of the length of the journal to their diameters (Lcp/d, Lmp/d) or to the diameter of the cylinder (Lcp/Dc, Lmp/Dc), etc.
RESULTS: Simple but physically understandable values have been obtained that characterize the operating conditions of the bearing, with the help of which, using the available catalogs of manufacturers, the designer has the opportunity to select the bearing shells closest to his, the designer’s, requirements – i.e., choose the type, size of the bearings and potential supplier.
CONCLUSIONS: The proposed method for selecting the design parameters of automobile engines bearings can significantly reduce the amount of computational work at the stage of preliminary design of the power mechanism (crankshaft-cylinder block-rod-piston group). The data presented in the work can also be useful for updating the long-outdated data presented in the educational literature of the 70s–90s.
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Hydraulic and pneumatic systems
Forecasting the energy characteristics of a reversible hydraulic machine for a head up to 250 m
Abstract
BACKGROUND: At present, in the pressure zone of 50–650 m for pumped storage power plants, hydroelectric units with classic single-stage radial-axial reversible hydraulic machines, which have a relatively simple design of the impeller and cylindrical guide vane, have received the most widespread energy performance, but are relatively quiet, large-sized and metal-intensive hydraulic machines. Numerical research and design of this type of machines are given special attention. The current trend is the design of flow parts based on numerical simulation of the flow. The most well-known commercial software products that implement finite volume numerical simulations are Ansys Fluent, Ansys CFX, StarCD, Numeca, Flow Vision and CADRUN. In the work under consideration, the calculations were performed using the Ansys CFX software package version 2021R1. Today, due to the lack of numerical capacity, the task of developing and using a technique that will allow obtaining an acceptable result with optimal time spent on data preparation and computational studies remains an urgent task.
AIMS: The aim of the work was to present an “economical” methodology for numerical simulation of energy characteristics.
METHODS: The methodology consists in describing the problem statement, the computational grids used, and the assumptions made for the optimal use of computing resources without a significant loss in the accuracy of the results.
Object of computational research: The presented article investigates the flow part of a radial-axial pump-turbine designed for application to a maximum head of up to 250 m.
RESULTS: Numerical modeling of power characteristics of on-pump and turbine modes is performed. A brief description of the problem statement, computational grids used, and assumptions made is given. A comparison of calculation results with experimental data of model tests is presented. The comparison results are presented in the relative form for the main parameters: pressure, efficiency, reduced rotational speed and flow rate.
CONCLUSIONS: It is recommended to use SST model of turbulence in a stationary statement in order to predict the power characteristics of pump-turbines. The use of economical block-structured grids, as well as the performing of calculations only in the region of one blade of the guide vanes, one impeller blade and a suction pipe with the use of preliminary results of calculations in a spiral chamber allow using computational resources optimally without significant loss of accuracy of the results.
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Determination of steam leaks through faulty labyrinth seals of a steam turbine
Abstract
BACKGROUND: When calculating the axial force acting on the thrust bearing of a steam turbine, when calculating the dimensions of the unloading piston, when calculating the efficiency of the turbine stages, it is necessary to determine the amount of steam leakage through its diaphragm and end seals. Existing methods make it possible to calculate leaks only through serviceable, undamaged labyrinth seals of several standard designs. However, during the operation of steam turbines, due to off-design axial and radial displacements of the rotor, labyrinth seals are often damaged - deformed, crushed or broken.
AIMS: The purpose of the study is to develop a method for calculating leaks using direct CFD modeling in serviceable and damaged seals with typical failures, verify the simulation results by comparison with known methods and experimental data, and determine critical steam leaks through faulty labyrinth turbine seals.
MATERIALS AND METHODS: A method for calculating the steam flow rate through serviceable and faulty labyrinth seals of a steam turbine using the capabilities of modern CFD methods is proposed and verified. The computational domain of modeling the front-end seal of the turbine, the features of setting the boundary conditions, the adaptive computational grid, and the numerical mathematical model used are described.
RESULTS: The results of a numerical study of steam leakage through serviceable and damaged labyrinth end seals of the turbine are presented: with bent ridges in the seals, with partial or complete absence of ridges. The operation of the front-end seal of the turbine was simulated with several typical failures. It is shown that partial damage to the ridges of the front-end seal of the turbine, which is often encountered during operation, leads to a significant increase in steam leakage. It has been established that with significant damage to the ridges, an increase in steam leakage can lead to the exhaustion of the capacity of the steam pressure regulator in the seal, which leads to a malfunction of the turbine thrust bearing unloading system.
CONCLUSIONS: The proposed technique and the results obtained can be used to calculate steam leakage through serviceable and faulty diaphragm and end labyrinth seals of turbines, when calculating the value of the axial force acting on the turbine thrust bearing in variable operating modes, the technique is useful in assessing the efficiency of the thrust bearing unloading system.
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The study of the possibility of the pumping unit optimization for two operation modes, different from the optimal one
Abstract
BACKGROUND: The study of factors affecting the vibroacoustic characteristics of pumps is one of the main areas of development in the current pump industry. Improvement of these characteristics allows to extend the service life of pumps by means of vibration levels reduction as well as to decrease the noise level.
AIMS: In this study, the attempt to optimize the flow part of a multi-stage pump was made in order to obtain acceptable noise, vibration and harshness (NVH) characteristics in two operation modes that are different front the optimal one.
METHODS: As the result of the study, it was found that changing these parameters in favour of NVH has a negative impact on the pump efficiency and vice versa. Thereby the optimal balance between these parameters should be found. The optimization was performed with the method of research of the parameter space with use of LP-tau sequences. The following elements were chosen as the optimization parameters: the area at the entrance to downstream, the angle of guide vanes at the entrance to the downstream, the width of rotor at the outlet, the angle of rotor vanes at the inlet and the outlet, the wrap angle of rotor vane. Decrease of the area of the graph of pressure pulsation spectrum was chosen as the optimization criteria. The mathematical model was verified with two designs of the flow part produced and tested earlier. The first sample has an overstated rate of the NVH spectrum in the area of high frequencies, the second sample has an overstated rate of the NVH spectrum in the area of low frequencies.
RESULTS: The compiled mathematical model proved its good quality, showing the same results, which allows to speak about the admissibility of its use for optimization of the flow parts of pumps.
CONCLUSIONS: This study will be useful for specialists in the field of vane hydraulic machines design.
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Transport and transport-technological complexes
Validation of the CAE model set for a passenger car suspension according to loading criteria
Abstract
BACKGROUND: Development of numerical methods and technology of computer-aided engineering, used in vehicle design, has reached its high level. Results of virtual experiments cannot be totally relied upon without verifying results obtained with the developed mathematical model. That is why the present paper concentrates on the relevant issue of validation of the CAE models, applicable for vehicle suspension components dynamic load analysis.
AIMS: Goal of the research is adequacy confirmation of developed requirements to preparation of simulation models, applicable for dynamic load and fatigue analysis, by means of numerical simulation with validation analysis.
METHODS: CAE models validation is carried out with a comparative method of results obtained from either laboratory or proving ground testing and simulation of a physical object. Strain gauging results are taken for the comparison. The Models are prepaired with using MBS and FEM technologies.
RESULTS: Validation showed of validation show a good convergence of modelling and experiment results, that confirm adequacy of developed requirements to creation of CAE models, applicable for load and fatigue analysis of vehicle suspension components. The selected convergence evaluation criteria have not been used in similar papers yet and have shown an effective outcome of quantitative and qualitative comparison of loading condition of suspension parts in a variety of boundary conditions of mechanical system simulation.
CONCLUSIONS: Validated CAE models of a passenger car suspension, developed accelerated loading cycle, the model design and dynamic loading simulation approach can be used for chassis parts load analysis and fatigue prediction during early stages of development and as support of testing.
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Control signal algorithm of the accelerator pedal providing an effective energy consumption by an electrobus traction gear
Abstract
BACKGROUND: At the present moment there become more electrobuses in big towns, and the problem of the increasing the their energy efficiency is actual in intertown traffic (that assumes stops and time limitation among stops) because of the limitated on-board capacitors.
AIMS: Development of the control signal algorithm of the accelerator pedal providing an effective energy consumption by an electrobus traction gear.
METHODS: The new method for control signal formation of the accelerator pedal is proposed. It has a feature that provides the system operation “traction gear – frequency converter” in zone of the increased efficiency factor and limits the velocity of control signal level growing when a driver tromps gas.
RESULTS: Analysis of the electrobus operation results in intertown traffic shows, that the aggregate average electric capacity, consumed at electrobus operating equipped with the energy saving systems, is less by 8,2% than at electrobus operating without energy-saving systems at the same conditions. The average efficiency factor of the “traction gear – frequency converter” system of an electrobus equipped with energy-saving systems has been increased by 4.5%. The time of driving on the route of an electrobus equipped with energy saving systems increased by 27 seconds that is an acceptable result. Energy saving in linehaul operation was provided only by an antislip system operation. During the total time driving of the electrobus energy saving was 2.6%.
CONCLUSIONS: A new method for generating a control signal from the side of the accelerator pedal is proposed, which differs in that it ensures the operation of the “traction motor – frequency converter” system in the zone of increased efficiency and limits the rate of increase in the level of the control action when the driver abruptly presses the accelerator pedal.
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Mathematical simulation of the automatic control of the tractor power unit
Abstract
BACKGROUND: Many manufacturers of agricultural tractors have machines with automatic gearboxes in their product line. The development of the design of this type of transmissions, the control system and the algorithm of its operation is an urgent technical task.
The article considers the issues of mathematical simulation of the working process of the automatic transmission of a wheeled tractor and the automatic transmission control system.
AIMS: The purpose of the work was to determine the optimal control laws of automatic control of a wheeled agricultural tractor engine and transmission in various operating modes using a digital model of the tractor transmission.
METHODS: Simulation of working conditions is performed in the Matlab program digital software packages and its applications – Simulink, Simscape. At the same time, with the help of fundamental data blocks of these applications, models of the physical components of the gearbox and the machine engine and the tractor power transmission control system, are created.
RESULTS: The application procedure of the MATLab–Simulink, Simscape software package for mathematical modeling of transmission operation control is considered. With the help of the developed mathematical model, a simulation of the tractor power unit operation in the main operating modes was carried out in order to optimize the characteristics of the tractor control system.
The scientific novelty of the research lies in the selection and optimization of the transmission control laws in accordance with the requirements to agricultural tractors with an automatic step gearbox.
CONCLUSION: The practical utility (value) of the research lies in the possibility of using the proposed control laws to develop a transmission control system for new tractors with an automatic step gearbox.
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Development of a dynamic model of a front loader for the analysis of operational properties and determination of loads acting on its elements
Abstract
BACKGROUND: For front-end loaders, it is important to minimize energy consumption when performing loading and unloading operations. To ensure competitive properties at a given time of folding links, lifting and with sufficient power of the steering and boom and bucket control drives. This requirement significantly affects the autonomy, versatility and, ultimately, the economic efficiency of loading and unloading operations.
AIMS: Development of a dynamic model of a front loader to determine various operational properties and loads in the joints when working in specified load conditions.
METHODS: A dynamic model has been developed and its operation has been simulated in a system for calculating the dynamics of coupled bodies. The mathematical model includes all the main elements of a front loader – drive axles, internal combustion engine, generator, steering hydraulic cylinders, cargo, bucket, rear axle, cab, wheels, bucket lifting and tipping mechanism, load-bearing system, support surface, TED drive of the driving wheels. The elements are modeled using graphical primitives, hinges and power ones from the standard library of the application for calculating the dynamics of connected bodies.
RESULTS: The article presents a description of a mathematical model of a front loader made in the application for the calculation of connected bodies. A typical list of load modes is presented and examples and simulation results are shown. Possible areas of use of the described mathematical model are shown.
CONCLUSIONS: The developed dynamic model of the front loader makes it possible to analyze various design solutions at the early stages of design, such as the model and number of electric motors, kinematics of the bucket lifting and tilting mechanism, steering kinematics, etc. for energy costs during typical operations. In addition, the developed dynamic model allows you to determine the loads in the hinges and power connections, which can be used when performing strength calculations or when selecting loader components.
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Electrotechnical complexes and systems
Mathematical model creation for the lithium-ion battery and its comparing with analogs
Abstract
BACKGROUND: With increased emphasis of world community on climat change problems automotive industry liders shift stress on the design and mass production of vehicles equipped with electric power plants. The battery as the most important and crucial part of any vehicle, in turn needs a detailed analysis on the stage of its digital prototype design. Accurate prediction for the designed battery performance and its real-time follow-up are possible only at using the adequate mathematical model of the battery.
AIMS: To study the existant simulating models for a lithiumion battery operation, to compair their results with the expaeriment data and to increase accuracy using the designed dynamic model considering the hysteresis processes.
MATERIALS AND METHODS: Modeling is fulfilled on the base of Matlab programme and using Simcenter Amesim simulation platform, that allowed to assemble the virtual stand for lithium-ion cell operation with the electric storage library components.
RESULTS: Cell operation model is created in Amesim, the basic principles for electrothermal modeling of an accumulator element considering the hysteresis. Script driven simulating the models in Amesim and Matlab software was carried out for the real electric engine cell loading at city movement. Model results have being compared with experimental data.
CONCLUSIONS: Practical value of the study is possibility of using the designed mathematical model for battery control system developement and for optimization of electromobile power equipment operation for account of the best quality of the models used.
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Technical electrogenerating tools for road facilities: systematics and design specifics
Abstract
BACKGROUND: Currently the Russian Federation Government has a strong focus to roads safety. This is due to the national project «Safe High-Quality Roads». One of tools of pedestrian safety in an urban are road bumps. They are need for drivers speed slow.
Contrarily world scientists create alternative sources of electrical energy. It led to tools type as technical electrogenerating devices.
Whereas technical electrogenerating tools have big amount of developments by russian and world scientists. But in modern scientific literature there is no systematic concept about this tools type.
AIMS: The paper purpose is knowledge summary about technical electrogenerating tools and develop their classification.
METHODS: Energy of a moving car is accumulated and converted into electrical energy by devices type. Concept of technical electrogenerating tools is based on convertion of energy pulse of speed bump into electrical energy at the moment of car runover. This energy can be used for electricity supply of road infrastructure (crosswalk lighting, road sign ligtht, powering traffic lights).
RESULTS: The basic classification feature of these tools is device type converting moving car energy into electrical energy: piezoelectric, hydraulic, electromechanical. In turn technical electrogenerating tools with electromechanical converter are classified by criteria: amount of motor, type of transmission mechanism, design of pressing platform and type of generator.
CONCLUSIONS: The developed classification provides to systematize contributions of russian and world scientists designing devices of technical electrogenerating tools.
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Forecasting the magnitude of the electrical load in electrical complexes of aircraft
Abstract
BACKGROUND: The issue of forecasting, analysis and control of electrical load becomes more significant both within the framework of the electrical complex of the summer apparatus as a whole, and for certain groups of electric energy consumers. Forecasting the electrical load is necessary to solve the problem of optimizing the operational state of an electrical complex or system, under constantly changing conditions and changing environment, which entails a change in power. Recently, a relatively new method has often been used, which is based on fuzzy logic. This method is a symbiosis of fuzzy logic and neural networks, which includes the main properties characteristic of these areas. Thanks to the use of a well-established fuzzy neural technology implemented in a correctly designed and trained fuzzy neural network for predicting electrical loads, it became possible to ensure sufficiently high accuracy and speed of load prediction.
AIMS: The purpose of the work is to analyze methods for predicting the electrical load of the aircraft’s electrical and technical complex, as well as to determine the most optimal methodology for predicting the electrical load of an autonomous aircraft used in the armed forces.
METHODS: Modeling of working conditions is performed in the Matlab program and its applications – Simulink. At the same time, with the help of the fundamental blocks of this application, models of the physical components of the electrical complex of the aircraft are created.
RESULTS: For a substantive assessment of the prediction of the magnitude of the electrical load of the electrical complex of the aircraft, an algorithm implemented on a computer has been developed. It provides for the implementation of retrospective calculations taking into account the amount of power generated, the duration of operation and the flow of electricity in the electrical complex as a whole.
CONCLUSIONS: Due to the use of a well-established fuzzy neural technology for predicting electrical loads, implemented in a correctly designed and equipped fuzzy neural network, it became possible to provide the necessary accuracy and speed of predicting electrical loads.
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