进气氧浓度对柴油机燃烧过程影响的仿真研究

为分析进气氧浓度对柴油机燃烧的影响，通过调节进气氮氧比控制进气氧浓度，应用计算流体力学（CFD）软件FIRE对不同进气氧浓度下柴油机燃烧过程进行了三维仿真研究。研究结果表明：进气氧浓度影响缸内混合气质量，进气氧浓度降低，缸内浓混合气增加，扩散燃烧阶段放热速率降低。随着进气氧浓度降低，缸内最高压力和平均温度降低，柴油机燃烧品质变差。富氧燃烧时柴油机NOx排放升高，碳烟排放降低；部分负荷时，进气氧浓度降低，NOx和碳烟排放均降低。

Simulation Study into Effect of Intake Air Oxygen Concentration on Combustion Process in Diesel Engine

In order to investigate the effect of intake air oxygen concentration on the combustion process in diesel engine, computation fluid dynamics (CFD) software FIRE is used to simulate the combustion process in terms of the ratio of oxygen and nitrogen in intake air. The results show that intake air oxygen concentration affects the quality of fuel-air mixture. With the decrease in intake air oxygen concentration, the rich fuel-air mixture increases, which leads to a decrease in heat release rate in the stage of diffusion combustion. The decrease in intake air oxygen concentration reduces the in-cylinder peak pressure and combustion temperature, and the quality of combustion becomes worse. The oxygen-enriched combustion leads to a remarkable increase in NOx emission and a decrease in soot emission; with a decrease in intake air oxygen concentration at part load, both NOx and soot emissions decrease.