不同进气组分对柴油机燃烧过程影响的研究  

A Study on the Effects of Different Intake Gas Constituents on the Combustion Process of Diesel Engine

作　　者：陈贵升[1] 朱文霞[1] 沈颖刚[1] 杨辉[1] 李伟东[1] 

机构地区：[1]昆明理工大学,云南省内燃机重点实验室,昆明650500

出　　处：《汽车工程》2016年第2期149-156,148,共9页Automotive Engineering

基　　金：国家自然科学基金(51366007);云南省应用基础研究面上项目(2013FB019);云南省级人才培训项目(KKSY201302127)资助

摘　　要：以正庚烷/甲苯/正己烯混合物简化机理作为柴油燃料燃烧化学反应动力学机理,应用计算流体动力学软件耦合化学动力学机理建立了某高压共轨柴油机的三维CFD数值模型。采用该耦合模型,以海拔3 000m大气环境(O_2和N2的体积分数分别为16.2%和83.8%)为基点,模拟对比了不同体积掺混比(1.6%,4.8%和8%)的进气组分(O_2,H_2,CO_2和气态H_2O)对发动机工作过程的影响。结果表明:进气掺O_2后,燃烧始点提前,预混燃烧比例减少,放热速率峰值降低,缸内活性基(OH,O)浓度升高,NO明显增大而碳烟(Soot)显著降低;进气掺H_2后,放热速率显著加快,缸内压力和峰值温度增高,NO稍有升高而Soot略为降低;进气掺CO_2后,着火时刻最晚,缸内温度和压力最低,A_4与C_2H_2的消耗反应持续期最长,其NO生成最少而Soot排放最高;进气掺气态H_2O后,NO稍有降低,而Soot变化不大。With the simplified mechanism of n-heptane / toluene /n-hexene compound as the chemical reaction kinetics mechanism of diesel fuel combustion,a 3D CFD numerical model for a high-pressure common-rail diesel engine is built by applying CFD software coupled with chemical kinetics mechanism. Using the coupled model built,with the atmospheric environment（ 16. 2% O2＋ 83. 8% N2 in volume fraction） at 3000 meters above sea level as reference,the effects of different volumetric blending proportions（ 1. 6%,4. 8% and 8%） of various intake gas constituents（ O2,H2,CO2 and gaseous H2O） on the combustion process of engine are comparatively simulated.The results show that with O2 blended,the starting point of combustion advances,the proportion of premixed combustion and the peak heat-release-rate reduce,the concentration of active radicals（ OH,O） in cylinder rise and NO emission significantly increases while soot emission decreases dramatically; With H2 added,the heat release rate sharply increases,in-cylinder pressure and peak temperature rise,and NO emission slightly increases while soot emission deceases a bit; The blending of CO2 leads to the latest ignition timing,the lowest in-cylinder pressure and peak temperature,the longest consumption reaction duration of A4 and C2H2,the least NO generation and the highest soot emission; And when gaseous H2 O is added,NO emission slightly reduces and soot emission has little change.

关 键 词：柴油机 进气组分 化学反应动力学 燃烧过程 排放特性 

分 类 号：TK421.2[动力工程及工程热物理—动力机械及工程]