对置活塞二冲程柴油机扫气系统优化方法研究

Study on Optimizing Method of Scavenging System of an Oppose-Piston Two-Stroke Diesel Engine

分析了对置二冲程柴油机扫气系统参数对发动机工作过程特征参数的影响规律,分别提出了以扫气效率为优化目标和以平均指示压力(IMEP)为优化目标的优化函数。结合正交优化方法,优化计算并对比分析不同优化函数的优缺点。研究结果表明:IMEP可有效地兼顾扫气系统参数对扫气效率与发动机指示热效率的影响,更适合作为对置二冲程柴油机扫气系统优化目标。优化结果显示:扫气口宽度比为0.85,排气口宽度比为0.6,扫气口高度为22mm,排气口高度为29mm,扫气口倾角为10°时发动机IMEP达到最优值。

The effect of scavenging parameters on the engine working process characteristic parameters was studied and two optimization functions with two different optimization objectives were established： scavenging efficiency was employed as one optimization objective while IMEP as the other one. Orthogonal experiment was used in an optimizing calculation. The results show that IMEP can comprehensively embodiment the effects of scavenging parameters on scavenging efficiency and indicated thermal efficiency and can be used as an optimization objective more effectively. And IMEP achieves maximum value when intake circular utilization is 0. 85, exhaust circular utilization 0.6,intake port height 22 mm,exhaust port height 29 mm, and port radial obliquity 10°.