喷油定时对柴油机性能影响的数值模拟

Numerical simulation study on influence of injection timing on diesel engine performance

为了研究喷油定时对柴油机性能的影响,对柴油机进行了燃烧性能模拟试验,以期获得柴油机的燃烧和排放在不同喷油定时下的变化规律。结果表明：喷油提前角为8～16°CA,着火始点随提前角线性减小;喷油提前角为8～13°CA,滞燃期变化不大,缸内燃油蒸发率波动较大,而在13～16°CA之间,提前角增大,滞燃期变长,燃油蒸发率线性增大;缸内的最高平均温度出现在上止点后10～20°CA之间,并随着喷油提前角的增加而增大;放热率峰值出现在上止点附近,喷油提前角越大,放热率的峰值越大,也越靠前;在上止点附近,NO的质量分数增长较快,在上止点后10～30°CA之间,增长趋势减缓,且喷油提前角越大,NO的排放越高。

In order to study the influence of injection timing on the engine performance,engine performance is simulated.Combustion and emission of engine are ob-tained under different fuel injection timing.The results show that：timing of combustion decreases linearly,when fuel injection advance angle is 8-16 °CA;Ignition delay period changes little and fuel evaporation rate changes widely,when fuel injection advance angle is 8-13°CA;Ignition delay becomes long and fuel evaporation rate increases linearly with advance angle increase,when fuel injection advance angle is 13-16°CA;The highest average temperature appears after TDC 10-20°CA,and it increase with fuel injection advance angle increase,the peak heat release rate appears near TDC,and it increase with fuel injection advance angle increase;The mass fraction of NO is growing faster near TDC,it grows slowly after TDC 10-30°CA,the NO emission is higher with fuel injection advance angle increase.