二次喷射策略对GDI发动机微粒排放影响规律的仿真研究  

Simulation Research on Influence of Secondary Injection Strategy on Particulate Emission of GDI Engine

作　　者：崔爽[1] 汪安东[2] 曲大为[2] 范茜[1] Cui Shuang;Wang Andong;Qu Dawei;Fan Qian(ChangChun Vocational Institute of Technology , Changchun 130033, China;Jinlin University, Changchun 130022, China)

机构地区：[1]长春职业技术学院,长春130033 [2]吉林大学,长春130022

出　　处：《机械科学与技术》2019年第6期884-891,共8页Mechanical Science and Technology for Aerospace Engineering

基　　金：国家自然科学基金项目(51306069)资助

摘　　要：为降低GDI发动机微粒排放,搭建了某型缸内直喷汽油机的三维数值模型并利用AVL-Fire对发动机微粒生成过程进行仿真模拟,探究缸内微粒的生成机理和两次喷油策略对微粒生成的影响规律。首先对原机喷油参数下的单次喷射策略进行了仿真研究,其次,在单次喷射的基础上进行了燃油两次喷射,探究喷油时刻及喷油比例对微粒生成的影响规律,得到了如下的研究结论:原机喷射策略下未完全蒸发的油膜遇到火焰时在油膜表面产生扩散燃烧导致微粒大量生成;二次喷射策略下,随第二次喷油时刻推迟,最终微粒质量分数和数量浓度均先减小后增加,优化后的二次喷油策略最终微粒质量分数为1.28×10^-11,最终微粒数量浓度为2.99×10^13,较单次喷射策略分别降低了46.89%和31.42%。因此,合理的制定二次喷油策略可以减少微粒的产生。In order to reduce the particulate emissions of GDI engines, a 3D numerical model of a certain type of cylinder direct injection gasoline engine was built and the AVL-Fire was used to simulate the generation process of engine particulates. The particulate generation mechanisms in cylinders and secondary injection strategies for particulates were investigated. The effect of the law is firstly simulated by the single injection strategy under the original fuel injection parameters. Secondly, two injections of fuel were performed based on the single injection to explore the influence of injection timing and the injection ratio on particle generation. According to the influence laws, the following conclusions have been obtained:in the original jet injection strategy, the incomplete evaporation of the oil film on the surface of the oil film caused diffusion combustion and resulted in the generation of large amounts of soot;Under the secondary injection strategy, as the second injection timing postponed, the final soot mass fraction and the number concentration firstly decreased and then increased. The optimized secondary fuel injection strategy has a final soot mass fraction of 1.28×10^-11 , and the final soot number concentration was 2.99×10^ 13 , which were 46.89% and 31.42% lower than the single injection strategy respectively. Therefore, a reasonable development of secondary injection strategy can reduce the production of soot.

关 键 词：GDI汽油机 二次喷射 微粒 CFD仿真分析 

分 类 号：TG156[金属学及工艺—热处理]