缸内直喷汽油机喷油及燃烧过程三维数值模拟

摘要

对某直喷汽油机部分负荷时的进气、喷油、混合气形成及燃烧过程进行了数值模拟.分析了喷油正时对混合气分布、燃烧性能及排放性能的影响.模拟结果显示,在喷油开始时刻为480°曲轴转角时混合气分布比较理想,达到了分层稀燃的目标.生成物NO的主要来源是参与燃烧的空气中的氮,NO的生成随温度的提高而急剧增加；炭烟生成的条件是高温和缺氧,局部较浓混合气相对缺氧导致炭烟生成.%The numerical simulations of intake, fuel injection, mixture formation and combustion process were carried out on a direct injection gasoline engine at partial loads. The influences of injection timing on mixture formation, combustion and emis- sion performance were analyzed. The results show that desired stratified lean burn can be realized at 480 ~CA. The resultant NO is mainly from the nitrogen of burning air, which increases with the increase of temperature. The soot forms under the con- ditions of high temperature and oxygen lack, especially in rich mixture.