A simulation technique for engine parameter optimization, which was developed by using the combination of a micro-genetic algorithm and a modified KIVA code, was applied to optimize the multi-pulse injection parameters of MULINBUMP compound combustion system. In this study, five-pulse injec-tion parameters were optimized and corresponding eleven injection parameters including the injection pres-sure, start-of-first-injection timing, fuel mass in each pulse injection and dwell time between consecutive pulse injections were determined by using the simulation technique. In the engine with optimized injection parameters the BSFC was decreased by 25.4%, and NOx and soot emissions were limited within the current level. These indicate that the micro-genetic algorithm is suited to optimize the engine parameters. The op-timized results indicate that, the combination of increasing injection pressure and using the progressively increasing injection rate can dramatically reduce beth droplet number in the cylinder and fuel impingement on the cylinder liner, promoting the homogeneous mixture formation. The precisely controlling of the tim-ing of later pulse injections can get favorable piston spray targeting to efficiently utilize the oxidizer in the bowl to increase the combustion efficiency.%利用基于微种群遗传算法和改进的KIVA程序搭建的发动机多参数优化模拟平台,开展了MULIN-BUMP复合燃烧系统多次脉冲喷油控制参数的优化研究.主要对5次脉冲喷射的喷油压力、喷油定时、各脉冲油量和脉冲间隔等11个参数进行优化.优化后发动机的油耗降低了25.4%,而NO<,x>和碳烟排放值限制在预先规定的范围内,这说明微种群遗传算法非常适合发动机多参数优化问题的求解.分析优化结果发现,提高喷油压力联合递增式的喷油规律能够显著减少燃烧室内油滴数密度和缸套"湿壁"油量,促进均匀混合气的形成;精确控制后期脉冲喷油时刻,使后期喷油落在燃烧室内,可以充分利用燃烧室凹坑内的新鲜空气,提高燃烧效率.
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