A frequency compensation control method for the opposed-piston two-stroke folded-cranktrain（ OPFC） diesel engine＇s common rail system is presented as a result of the study of the loop-shaping theory. A common rail ...A frequency compensation control method for the opposed-piston two-stroke folded-cranktrain（ OPFC） diesel engine＇s common rail system is presented as a result of the study of the loop-shaping theory. A common rail working process and the classical frequency control theory are combined to construct a frequency restriction of common rail pressure. A frequency compensator is utilized to improve the robustness of multiplicative perturbations and disturbance. The loop-shaping method has been applied to design the common rail pressure controller of the OPFC diesel engine. Simulation and bench test results show that in the condition of perturbation that comes from the effect of injection,multi-injection,fuel pumping of a pre-cylinder,and instantaneous pressure fluctuation,the controller indicates high precision. Compared with the original controller,this method improves the control precision by 67. 3%.展开更多
The in-cylinder gas exchange process is crucial to the power performance of two-stroke aircraft piston engines,which is easily influenced by complex factors such as high-altitude performance variation and in-cylinder ...The in-cylinder gas exchange process is crucial to the power performance of two-stroke aircraft piston engines,which is easily influenced by complex factors such as high-altitude performance variation and in-cylinder flow characteristics.This paper reviews the development history and characteristics of gas exchange types,as well as the current state of theory and the validation methods of gas exchange technology,while also discusses the trends of cutting-edge technologies in the field.This paper provides a theoretical foundation for the optimization and engineering design of gas exchange systems and,more importantly,points out that the innovation of gas exchange types,the modification of theoretical models,and the technology of variable airflow organization are the key future research directions in this field.展开更多
In order to improve the thermal power conversion capacity of the internal combustion engine,combined with existing opposed-piston two-stroke engine（ OP2S） and hydraulic free piston engine（HFPE）,the integral struct...In order to improve the thermal power conversion capacity of the internal combustion engine,combined with existing opposed-piston two-stroke engine（ OP2S） and hydraulic free piston engine（HFPE）,the integral structure for a newtype of opposed-piston hydraulic-output（ OPHO） engine has been designed,an operating principle has been introduced,the composition of its synchronous drive mechanism has been carefully analyzed,and a mathematical model has been built. In addition,the kinematics models of both the mechanism and the conventional crank-link mechanism have been established by utilizing MATLAB,and the movement rules of the pivotal moving components have been obtained. According to the simulation results,the piston movement of this newtype of opposed-piston hydraulic-output engine reveals a prominent asymmetry compared to the conventional crank-link engine. Under a fixed engine revolving speed,the compression time of the opposedpiston hydraulic-output engine is shortened while the expanding time is lengthened,thus the gas turbulence intensity is strengthened around the top dead center（ TDC） position. Meanwhile,the piston obtains a longer isometric process compared to conventional engines,which could be benefitial to enhance the combustion efficiency.展开更多
The effects of various split injection strategies on the opposed-piston opposed-cylinder(OPOC)diesel engine combustion and emission characteristics have been studied numerically using AVL-Fire CFD tools.The five rate-...The effects of various split injection strategies on the opposed-piston opposed-cylinder(OPOC)diesel engine combustion and emission characteristics have been studied numerically using AVL-Fire CFD tools.The five rate-shaped main injections were used in split injection strategies.The results show that ignition delay from a rectangular injection rate is the shortest.Maximum pressure of the trapezoid injection rate is the largest.And the NOx emission of the rectangular injection rate is the largest.Meanwhile,the soot emission of the trapezoid injection rate is the least among the five injection rates.展开更多
为寻求对置活塞二冲程(Opposed Piston Two Stroke,OP2S)发动机换气品质提升的方法,开展进气条件和气口参数对OP2S发动机流通特性和缸内涡流特性的影响研究。采用气道稳流试验和计算流体力学仿真相结合的方法,分析了进气压力、换气压差...为寻求对置活塞二冲程(Opposed Piston Two Stroke,OP2S)发动机换气品质提升的方法,开展进气条件和气口参数对OP2S发动机流通特性和缸内涡流特性的影响研究。采用气道稳流试验和计算流体力学仿真相结合的方法,分析了进气压力、换气压差、气口升程和气口倾角4种参数对流量系数与涡流比的影响规律。研究结果表明:增大换气压差能够提高气体流速,通过增强气体惯性抑制气口处分离区的形成,从而显著提高流量系数和涡流比;增加气口升程会加强气口侧壁面处的流动分离现象导致流量系数减小,同时影响缸内速度分布,使涡流比增长趋势逐渐变缓;在顺时针旋流导向的气口构型中,左侧倾角采用大角度,左侧倾角的变化对流量系数影响较小,增大右侧倾角会扩大气口壁面分离区导致流量系数减小,增大两侧倾角均会明显提高气流切向速度使涡流比增大。展开更多
This study is an optimized extension based on the authors’previous research on the tribo-chemical reaction under constant temperature field of two-stroke internal combustion engines(ICEs).It establishes a coupled ana...This study is an optimized extension based on the authors’previous research on the tribo-chemical reaction under constant temperature field of two-stroke internal combustion engines(ICEs).It establishes a coupled analysis model that considers the tribo-chemical reactions,dynamic contact,and interface lubrication of the piston ring-cylinder liner(PRCL)system under transient temperature conditions.In this study,for the first time,the prediction of the tribofilm thickness and its influence on the surface micro-topography(the comprehensive roughness)are coupled in the working temperature field of the PRCL system,forming an effective model framework and providing a model basis and analytical basis for subsequent research.This study findings reveal that by incorporating temperature and tribofilm into the simulation model,the average friction deviation throughout the stroke decreases from 8.92%to 0.93%when compared to experimental results.Moreover,the deviation during the combustion regime reduces from 39.56%to 7.34%.The proposed coupled model provides a valuable tool for the evaluation of lubrication performance of the PRCL system and supports the analysis software forward design in two-stroke ICEs.展开更多
The results of a study of the acoustic characteristics of an aviation opposed piston engine are presented.The tests were carried out during the run of the power plants of the light propeller-driven aircraft F30,MAI-22...The results of a study of the acoustic characteristics of an aviation opposed piston engine are presented.The tests were carried out during the run of the power plants of the light propeller-driven aircraft F30,MAI-223M and MAI-890U under static conditions at the local aerodrome of Moscow Aviation Institute(National Research University).The influence of cowling on the energy characteristics of the sound field of the engine is considered.The influence of the engine power condition on the directivity of the tonal components of its radiation is studied.The dependences of the sound power on engine speed are obtained.展开更多
基金Supported by the National Natural Science Foundation of China(51406013)
文摘A frequency compensation control method for the opposed-piston two-stroke folded-cranktrain（ OPFC） diesel engine＇s common rail system is presented as a result of the study of the loop-shaping theory. A common rail working process and the classical frequency control theory are combined to construct a frequency restriction of common rail pressure. A frequency compensator is utilized to improve the robustness of multiplicative perturbations and disturbance. The loop-shaping method has been applied to design the common rail pressure controller of the OPFC diesel engine. Simulation and bench test results show that in the condition of perturbation that comes from the effect of injection,multi-injection,fuel pumping of a pre-cylinder,and instantaneous pressure fluctuation,the controller indicates high precision. Compared with the original controller,this method improves the control precision by 67. 3%.
基金funded by the National Natural Science Foundation of China(Nos.52206131,U2233213and 51775025)the National Key R&D Program of China(2022YFB2602002,2018YFB0104100)+1 种基金the Zhejiang Provincial Natural Science Foundation of China(LQ22E060004)the Science Center of Gas Turbine Project,China(No.P2022-A-I-001-001)。
文摘The in-cylinder gas exchange process is crucial to the power performance of two-stroke aircraft piston engines,which is easily influenced by complex factors such as high-altitude performance variation and in-cylinder flow characteristics.This paper reviews the development history and characteristics of gas exchange types,as well as the current state of theory and the validation methods of gas exchange technology,while also discusses the trends of cutting-edge technologies in the field.This paper provides a theoretical foundation for the optimization and engineering design of gas exchange systems and,more importantly,points out that the innovation of gas exchange types,the modification of theoretical models,and the technology of variable airflow organization are the key future research directions in this field.
基金Supported by the Basic Research Projects of National Ministries and Commissions(62201070215)
文摘In order to improve the thermal power conversion capacity of the internal combustion engine,combined with existing opposed-piston two-stroke engine（ OP2S） and hydraulic free piston engine（HFPE）,the integral structure for a newtype of opposed-piston hydraulic-output（ OPHO） engine has been designed,an operating principle has been introduced,the composition of its synchronous drive mechanism has been carefully analyzed,and a mathematical model has been built. In addition,the kinematics models of both the mechanism and the conventional crank-link mechanism have been established by utilizing MATLAB,and the movement rules of the pivotal moving components have been obtained. According to the simulation results,the piston movement of this newtype of opposed-piston hydraulic-output engine reveals a prominent asymmetry compared to the conventional crank-link engine. Under a fixed engine revolving speed,the compression time of the opposedpiston hydraulic-output engine is shortened while the expanding time is lengthened,thus the gas turbulence intensity is strengthened around the top dead center（ TDC） position. Meanwhile,the piston obtains a longer isometric process compared to conventional engines,which could be benefitial to enhance the combustion efficiency.
基金Supported by the National Natural Science Foundation of China(51605447)
文摘The effects of various split injection strategies on the opposed-piston opposed-cylinder(OPOC)diesel engine combustion and emission characteristics have been studied numerically using AVL-Fire CFD tools.The five rate-shaped main injections were used in split injection strategies.The results show that ignition delay from a rectangular injection rate is the shortest.Maximum pressure of the trapezoid injection rate is the largest.And the NOx emission of the rectangular injection rate is the largest.Meanwhile,the soot emission of the trapezoid injection rate is the least among the five injection rates.
文摘为寻求对置活塞二冲程(Opposed Piston Two Stroke,OP2S)发动机换气品质提升的方法,开展进气条件和气口参数对OP2S发动机流通特性和缸内涡流特性的影响研究。采用气道稳流试验和计算流体力学仿真相结合的方法,分析了进气压力、换气压差、气口升程和气口倾角4种参数对流量系数与涡流比的影响规律。研究结果表明:增大换气压差能够提高气体流速,通过增强气体惯性抑制气口处分离区的形成,从而显著提高流量系数和涡流比;增加气口升程会加强气口侧壁面处的流动分离现象导致流量系数减小,同时影响缸内速度分布,使涡流比增长趋势逐渐变缓;在顺时针旋流导向的气口构型中,左侧倾角采用大角度,左侧倾角的变化对流量系数影响较小,增大右侧倾角会扩大气口壁面分离区导致流量系数减小,增大两侧倾角均会明显提高气流切向速度使涡流比增大。
基金supported by the Shandong Provincial Natural Science Foundation(No.ZR2022QE183).
文摘This study is an optimized extension based on the authors’previous research on the tribo-chemical reaction under constant temperature field of two-stroke internal combustion engines(ICEs).It establishes a coupled analysis model that considers the tribo-chemical reactions,dynamic contact,and interface lubrication of the piston ring-cylinder liner(PRCL)system under transient temperature conditions.In this study,for the first time,the prediction of the tribofilm thickness and its influence on the surface micro-topography(the comprehensive roughness)are coupled in the working temperature field of the PRCL system,forming an effective model framework and providing a model basis and analytical basis for subsequent research.This study findings reveal that by incorporating temperature and tribofilm into the simulation model,the average friction deviation throughout the stroke decreases from 8.92%to 0.93%when compared to experimental results.Moreover,the deviation during the combustion regime reduces from 39.56%to 7.34%.The proposed coupled model provides a valuable tool for the evaluation of lubrication performance of the PRCL system and supports the analysis software forward design in two-stroke ICEs.
文摘The results of a study of the acoustic characteristics of an aviation opposed piston engine are presented.The tests were carried out during the run of the power plants of the light propeller-driven aircraft F30,MAI-223M and MAI-890U under static conditions at the local aerodrome of Moscow Aviation Institute(National Research University).The influence of cowling on the energy characteristics of the sound field of the engine is considered.The influence of the engine power condition on the directivity of the tonal components of its radiation is studied.The dependences of the sound power on engine speed are obtained.
