二次喷射对直喷增压小排量汽油机影响的数值模拟

摘要

A numerical simulation is conducted on a downsized turbo-charged gasoline direct injection en-gine with the models for fuel spray and combustion verified by tests to study the effects of second injection ( different injection timing and injected fuel quantity proportion) on the formation of fuel film and the uniformity of mixture. The results show that in low-speed full load condition, there exist an optimal set of injection parameters for split in-jection:first injection starts at 60oCA ATDC, second injection ends at 170oCA ATDC, and the second injection shares 30% of total fuel injected.%采用经试验验证的喷雾和燃烧模型,对一款小排量增压直喷汽油机进行数值模拟,研究二次喷射(不同喷油时刻和喷油比例)对发动机的油膜形成和混合气均匀性的影响。结果表明,在低速全负荷工况下,该款发动机存在一组最佳喷油参数：第一次喷射开始时刻为60ºCA ATDC,第二次喷射结束时刻为170ºCA ATDC,第二次喷射燃油比例为30%。