喷油定时和涡流比对低温燃烧影响的模拟研究

A Simulation Study on the Effect of Start-of-Injection and Swirl Rate on the Low Temperature Combustion

摘要:

基于CFD模拟软件，对一台柴油机进行低温燃烧模拟研究，对比分析不同EGR率、喷油定时和涡流比对燃烧和排放的影响。结果表明，随着EGR率的增大，燃烧放热过程滞后，缸内压力、温度和放热率峰值和累计放热量降低，NOx排放大幅降低的同时，soot、UHC和CO排放增加；在固定EGR率为40%的同时将喷油定时从353°CA提前至345°CA，可使燃烧放热过程适当提前，并有利于提高热效率和改善燃油经济性；在保持EGR率为40%，喷油定时为345°CA时，适度提高涡流比（从1.0提高至3.0），可有效减少soot、UHC和CO排放。

Abstract:

Based on the CFD simulation software, a study on the effect of the EGR, start of injection and swirl rate on the low temperature combustion is conducted. The results show that the combustion and heat release lag, meanwhile the cylinder pressure, temperature, peak of heat release rate and accumulated heat release decrease with the increased EGR rate. Besides, NOx emissions decrease drastically with the increased EGR rate, while soot, UHC and CO emissions increase. When the EGR rate is kept constant at 40%, and the start of injection is advanced from 353°CA to 345°CA, the combustion and heat release are advanced, the efficiency and fuel economy are improved. When the EGR rate and start of injection are kept constant at 40% and 345°CA, and the swirl rate is increased from 1.0 to 3.0, the soot, UHC and CO emissions is decreased.