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首先数值解析了缸内电控直喷汽油机的混合气形成过程,并且与光学纹影实验结果比较,验证了解析方法的可行性。在此基础上,分别考察了电控LPG直喷发动机曲面活塞顶燃烧室和凹坑型活塞顶燃烧室在部分负荷工况下混合气的形成过程。结果表明:在部分负荷下、压缩行程后期喷射时,由于缸内滚流的作用,两种不同形状活塞顶的燃烧室在接近压缩终了时,缸内混合气都能呈明显分层构造,即在火花塞附近聚集了较浓的混合气,而离火花塞较远处则是较稀的混合气,整个燃烧室的空燃比达到40∶1。
Firstly, the formation process of the mixture in the direct injection gasoline engine is analyzed numerically, and compared with the experimental results of the optical stripe, the feasibility of the analytical method is verified. On this basis, the formation process of mixed gas under partial load was investigated respectively for the piston combustion chamber and the pit-top combustion chamber of electrically controlled LPG direct injection engine. The results show that at the partial load, during the late stage of compression stroke, the mixture in the cylinder can show a distinct layered structure near the end of compression due to the effect of tumble flow in the cylinder. Concentrated in the vicinity of the spark plug gathers the mixture, and away from the spark plug is a more dilute mixture, the entire combustion chamber air-fuel ratio of 40: 1.