直线发动机起动及怠速燃烧特性仿真与优化

通过建立GT-Power发动机仿真模型研究直线发动机的起动及怠速过程的燃烧特性,利用发动机台架实验获取的缸压数据和GT-Power仿真结果的对比,验证了仿真模型的准确性,分析不同点火时刻及过量空气系数对直线发动机起动定转速下燃烧特性的影响,并对怠速控制参数进行寻优研究.结果表明:在相同过量空气系数下,推迟点火时刻从-50°(上止点之前,下同)到20°,直线发动机后燃现象逐渐增多,并在点火时刻为-40°时,缸压峰值、瞬时放热率峰值最大以及累积放热总量均达到最大值;在相同的点火时刻下,减小过量空气系数从1.62到0.62,直线发动机缸内压力峰值先增后减,在过量空气系数为0.83时,直线发动机缸压峰值、瞬时放热率峰值最大,累积放热总量较多.

Simulation and Optimization on Combustion Characteristics of Linear Engine System in Starting and Idle Process

The primary goal of this research is to build an engine simulation model through GT Power to study the combustion characteristics of linear engine system in starting and idle process. The cylinder pressure data collected from engine experiment were used to verify the simulation model. Based on this simulation model, the influence of the excess air coefficient and ignition advance angle on combustion characteristics of the linear engine system in constant revolution was studied and the control parameter in idle process was optimized. The results show that the ignition time being advanced from -50°(before the top dead center) to 20°under a constant excess air coefficient, the cylinder pressure, the instantaneous heat release rate and the total heat release all reach their largest peak value when the ignition advance angle is -40°. Reducing the excess air ratio from 1.62 to 0.62 under a constant ignition advance angle, the cylinder pressure and the instantaneous heat release rate all reach their largest peak value and the total heat release is large when the excess air ratio is 0.83.