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  

Influence of ultra-high pressure injection on mixed gas formation,combustion and emission characteristics of DI diesel engine

作　　者：江涛[1] 林学东[1] 李德刚[1] 

机构地区：[1]吉林大学汽车仿真与控制国家重点实验室,长春130022

出　　处：《吉林大学学报（工学版）》2016年第5期1484-1493,共10页Journal of Jilin University:Engineering and Technology Edition

基　　金：吉林省科技发展计划项目(20150101032JC)

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。The effect of ultra-high pressure injection on the formation mechanism of mixed gas and on combustion process is studied.The influence of high pressure injection on the spray characteristics and the concentration field etc is analyzed;the influence of high pressure injection on the jet number and its variation law in different space positions in the injection direction is also analyzed on a CR 2.0L direct injection diesel engine.Both simulation and experiments are carried out to predict the influence of ultra-high pressure injection on the engine performance.Results show that,as the injection pressure appropriately increases the jet number increases and the range of jet number expands,the spray quality is improved and the duration of combustion is shortened.High injection pressure also can reduce the thickness of the fuel film and the residence time in the combustion chamber wall,thus,the emission of HC is reduced.However,high pressure injection may lead to over high averagecombustion temperature inside the cylinder,which results the increases not only in NO emission but also in CO emission because of CO2 high temperature decomposition.

关 键 词：动力机械工程 直喷柴油机 高压喷射 喷雾特性 Jet数 燃烧 排放 

分 类 号：TK421.2[动力工程及工程热物理—动力机械及工程]