甲醇/柴油双直喷型JCCI发动机多参数优化研究

The methanol/diesel jet controlled compression ignition(JCCI)mode with dual-direct injection has been demonstrated to have good economy and emission performance.The dual-direct injection system has higher flexibility and more complex parameter effects,the three-dimensional numerical simulation combined with optimization algorithm and sensitivity analysis were used in this study to investigate the influence of multiple-parameter on the performance of 186FA engine at 75%engine load.The optimization results show that the initial temperature is between 421.8～431.1 K,the methanol substitution ratio(MSR)is 78.9%～80.8%,and the diesel jet-injection timing is between-26.64～-22.77 °CA ATDC,which can achieve high economy and emission performance simultaneously.The comparative analysis results of three typical cases show that case2 with late methanol pre-injection timing and diesel jet-injection timing has the best performance,and it presents a typical two-stage high-temperature rapid heat release characteristics.The sensitivity analysis results show that the MSR,initial temperature and diesel jet-injection timing have the most significant effects on the economy performance of methanol/diesel JCCI engine with dual direct injection,while the initial pressure has a weak effect on the engine performance,and soot emission shows a lower level overall.