超高压喷射对直喷柴油机混合气形成、燃烧及排放特性的影响

发布时间：2018-06-09 02:35

本文选题：动力机械工程 + 直喷柴油机　；参考：《吉林大学学报(工学版)》2016年05期

【摘要】：为了分析高压喷射对混合气的形成和燃烧排放特性的影响,在自行开发燃烧系统的2.0LCR直喷柴油机上,仿真分析了喷射压力对喷雾特性以及浓度场等微观物理场的影响,并引入表征两相流中液滴破碎作用强度的无量纲的Jet数,分析了在喷射方向不同空间位置上喷射压力对Jet数及其变化规律的影响;在此基础上通过试验和仿真相结合,预测分析了高压喷射对发动机性能的影响。结果表明:当提高喷射压力时,Jet数会增加,Jet数的变化范围会增大,还可改善喷雾质量,促进混合气的形成,缩短燃烧持续期,而且有利于减小燃烧室壁面形成的油膜厚度及其滞留时间,从而降低HC排放。但超高压喷射时会导致缸内平均燃烧温度过高,不仅NO排放增加,而且会造成CO_2高温分解使CO排放增加。
[Abstract]:In order to analyze the influence of high pressure injection on the formation of mixture and combustion emission characteristics, the effects of injection pressure on spray characteristics and concentration field were simulated on a 2.0LCR direct injection diesel engine. The dimensionless Jet number, which characterizes the action intensity of droplet breakage in two-phase flow, is introduced to analyze the influence of jet pressure on jet number and its variation law at different space positions in different injection directions, and based on this, the experiments are combined with simulation. The influence of high pressure injection on engine performance is predicted and analyzed. The results show that when the jet pressure is increased, the range of jet number increases, the spray quality is improved, the mixture formation is promoted, and the combustion duration is shortened. Moreover, it is beneficial to reduce the thickness of oil film formed on the wall of combustion chamber and its retention time, thus reducing the HC emission. However, UHP injection will lead to the excessive average combustion temperature in the cylinder, which not only increases the no emission, but also results in the CO emission increasing due to the decomposition of COSP _ 2 at high temperature.
【作者单位】：吉林大学汽车仿真与控制国家重点实验室;
【基金】：吉林省科技发展计划项目(20150101032JC)
【分类号】：TK421

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