摘要
通过一维流体动力学软件GT-Power与化学动力学软件CHEMKIN联合模拟发动机循环,建立乙醇燃料排气道EGR模型,研究了发动机CAI燃烧的控制因素。分析了排气道EGR策略中的排气门晚关、进气门晚开和进气门开启时刻与排气门关闭时刻同时变化3种配气定时方案对EGR率的影响。由模拟计算可知排气道EGR策略对发动机缸内的换气过程、燃烧过程有强烈的影响。模拟结果表明:随着排气门逐渐晚关,EGR率增大,进气门关闭时刻缸内温度升高;进气门晚开策略中,EGR率受进气回流的影响较大;排气门晚关、进气门晚开同时变化策略扩大了CAI燃烧的EGR率范围;适当的EGR率有利于CAI燃烧的实现,EGR率过低或过高将导致失火和爆震,在不同的转速下EGR率的分布也不相同。
With the GT-Power one-dimensional fluid dynamics software and CHEMKIN chemical kinetics software, the engine test cycle was simulated, the exhaust duct EGR model based on ethanol fuel was built and the control factors of CAt combustion were researched. The influences of exhaust valve late closing, intake valve late opening and the simultaneous variations of intake valve opening moment and exhaust valve closing moment on EGR rate were analyzed. By the numerical simulation, the in-cylinder gas exchange and combustion process were found to be strongly influenced by the exhaust duct EGR. The results show that the exhaust valve late closing results in the increase of EGR rate. The cylinder temperature increases at the moment of intake valve closing. In the strategy of intake valve late closing, the EGR rate is seriously affected by the intake reeirculation. In the strategies of simultaneous variations of exhaust valve late closing and intake valve late opening, the range of EGR rate is extended. The appropriate EGR rate is beneficial to CAI combustion while the lower or higher EGR rate will lead to the misfire and knock. In addition, the distributions of EGR rate are different at different speeds.
出处
《车用发动机》
北大核心
2009年第3期10-14,19,共6页
Vehicle Engine
基金
国家重点基础研究发展规划资助项目(2007CB210004)
关键词
乙醇
可控自燃
配气定时
排气道
废气再循环
数值模拟
ethanol
controlled auto-ignition （CAI）
valve timing
exhaust duct
EGR
numerical simulation
