Mixture formation analysis of an opposed-piston two-stroke gasoline-direct-injection engine

The effects of different flow forms on an opposed-piston two-stroke (OPTS) gasoline-direct-injection (GDI) engine was studied by analyzing the mixture formation and combustion. Swirl was broken and dissipated gradually and the turbulence kinetic energy (TKE) was small in the compression process; however, tumble was strengthened and the TKE was strong in the compression process. For swirl around X axis (the axis of cylinder) and tumble around Y axis (the vertical direction of injector), droplets were attached to the cylinder liner by the centrifugal force and the mixture distribution was poor. For tumble around Z axis (the direction of injector), the wall film in cylinder liner was thin and mixture distribution was homogeneous. Results showed that since the injector were installed on the wall of the cylinder liner in the OPTS-GDI engine, the spray angle was small and the mixture formation time was short. The 45° oblique axis tumble ratio of 1 was reasonable for the mixture formation and combustion for an OPTS-GDI engine.     

Study on Calibrating of Electronic Governors

The control parameters of electronic governor that influence the transient characteristics of the engine are analyzed. An electric control unit was developed and the control parameters were calibrated on the test bench. The initial value of integral term and the maximum output of rack position proportion, integration and derivation (PID) controller affect the step and triangle response drastically. Through correcting the proportional term and integral term of speed PID controller, the dynamic speed drop and speed overshoot are improved. A property control strategy for cold starting an engine is set, and the calibration process indicates that the fuel injected into the cylinder per cycle and the desired speed ascend rate drastically affect the start transient process.     

两冲程发动机轿车的噪声控制

目的控制两冲程发动机汽车噪声,方法在对汽车进行噪声源识别的基础上改进消声器设计,设计安装隔声罩．结果汽车车外加速噪声满足国家标准。结论采取合理的噪声控制措施可以将两冲程汽车噪声控制在规定范围内,达到与四冲程发动机相当的水平。     

缸内直喷汽油机的HC排放特性分析及未来排放法规对其的挑战性

在介绍缸内直接喷射汽油机基本燃烧机理及各工况运行特点的基础上 ,重点分析了缸内直喷汽油机的HC排放机理 ,同时基于对比试验 ,分析比较了在FTP 75测试循环下缸内直喷汽油机与进气道喷射汽油机的HC排放特性 .分析表明 ,为了满足未来严格的排放法规的要求 ,缸内直喷汽油机仍面临着巨大的挑战 .此外还分析了造成缸内直喷汽油机HC排放高的原因 ,并提出了控制措施 .     

柴油机喷油器内部流动和缸内喷雾燃烧的联合模拟

利用FIRE等软件,以AIAA的V&V准则为指导,对简单喷油器模型内部流动进行了校核计算,提高了Deutz1013柴油机喷油器内部穴蚀两相流动模拟的可靠性,并通过接口文件,实现了喷油器内部流动与缸内喷雾、燃烧的联合模拟,比较了柴油雾化燃烧的传统模拟方法和联合模拟方法的差异,分析了柴油的初次破碎对雾化和燃烧的影响,有利于喷油器的优化设计和柴油机燃烧的参数匹配.结果表明,AIAA的V&V准则可以大幅度提高数值模拟的精度和可靠性,而且喷油器内部产生的穴蚀对柴油的雾化和燃烧有很大影响.     

履带车辆电传动发动机-发电机组及其控制策略研究

根据电传动系统的结构特点,分析了传统机械传动结构与电传动结构在控制方面和能量耦合方面的差异,提出了电传动结构各个传动子系统之间能量弱耦合这一特点,定义了发动机-发电机组的功能;提出发动机、发电机的选型要求,设计了发动机-发电机组与负载的连接电路;根据发动机和发电机的工作特性,划分了几种工作模式,提出了以动力性为主,兼顾发动机发电机组的效率,实现最优控制的控制策略.     

进气氧浓度对柴油机燃烧过程影响的仿真研究

为分析进气氧浓度对柴油机燃烧的影响,通过调节进气氮氧比控制进气氧浓度,应用计算流体力学（CFD）软件FIRE对不同进气氧浓度下柴油机燃烧过程进行了三维仿真研究。研究结果表明：进气氧浓度影响缸内混合气质量,进气氧浓度降低,缸内浓混合气增加,扩散燃烧阶段放热速率降低。随着进气氧浓度降低,缸内最高压力和平均温度降低,柴油机燃烧品质变差。富氧燃烧时柴油机NOx排放升高,碳烟排放降低;部分负荷时,进气氧浓度降低,NOx和碳烟排放均降低。     

基于负荷前馈的增压柴油机转速控制算法研究

为提高履带车辆发动机转速的抗负荷扰动性,并改善整车行驶过程的转速控制效果,在基于转矩控制架构下设计了前馈-反馈全程调速控制算法。该算法基于平均值模型和曲轴动力学模型设计发动机负荷估计算法,利用某6缸直列泵柴油机进行台架试验研究其在稳态动态工况的估计精度。进行了动力传动系统仿真研究,研究结果表明：该算法能够显著提高转速控制的抗负荷扰动能力;在整车加速过程中保持了较快的转速调节时间,避免了控制参数的重复标定;踏板-转速跟随特性的提高能够减少履带车辆意外换挡的出现。