混合气浓度对缸内直喷汽油机微粒生成过程影响研究

Study on the Excess Air Coefficient Effect on Particulate Formation Process of Gasoline Direct Injection Engine

通过对某475GDI发动机进行数学建模和仿真计算,分析不同混合气浓度对微粒生成过程的影响规律。结果表明随着过量空气系数的逐渐增大,也就是混合气逐渐变稀,微粒质量分数和数量浓度逐渐降低,缸内燃烧温度逐渐降低,缸内平均压力呈现先增加后减小的趋势,并且缸内的燃烧过程迟后。无论混合气浓度如何变化,高浓度混合气区域主要集中在燃烧室左右两侧靠近壁面的位置,也正是燃烧室形状最复杂、缸内气体流动状态最差的区域,易于产生微粒。

Through mathematical modeling and simulation of a 475 GDI engine,the effect of different excess air coefficient on the particle formation process were analyzed. The results showed that with the gradual increase of the excess air coefficient,which is mixed gas gradually thinning,particulate mass fraction and number concentration decreases,the combustion temperature gradually reduced,the cylinder pressure showed the trend of first increased and then decreased,and combustion process later. Regardless of the mixture gas concentration changes,high concentration mixed gas area is mainly concentrated in the left and the right sides of chamber located near the surface of the wall where the combustion chamber with complicated shape. It is easy to produce higher particles because the area flowability is poor.