直喷式汽油机缸内浓度场数值模拟

Numerical Simulation of Fuel Distribution in Cylinder of DI Gasoline Engine

对直喷式二冲程汽油机缸内浓度场进行了数值模拟,选取两种代表性的发动机工况,采用球顶燃烧室,改变喷油定时和喷雾方向,研究它们对燃烧室内混合气浓度分布的影响。通过仿真分析得到:喷油定时和喷油方向对缸内浓度场分布有很大影响。当喷油器的中心轴线与气缸中心轴线的夹角为15°的喷油方向,喷油定时在低负荷选择95°CA、高负荷选择160°CA时,可以在火花塞附近形成有利于点火的混合气浓度,在整个燃烧室形成有利于分层燃烧的浓度场分布。

The fuel distribution in cylinder was simulated numerically in a two-stroke, DI gasoline engine with hemispherical shape combustion chamber for two typical operation conditions to investigate the effect of various fuel injection timing and spray direction on it. Results show that fuel injection timing and spray direction have an important influence on in-cylinder fuel distribution, and the best mixture distribution beneficial to either ignition of the spark plug or stratified combustion in whole combustion chamber can be achieved with the spray direction at angle of 15 degree to the cylinder centre line, and the injection timing at 95 °CA BTDC for low load range, at 160°CA BTDC for high load range.