燃烧室形状对大功率机车柴油机工作性能的影响

针对大功率铁路机车柴油机的工作过程进行仿真计算,仿真计算得到的数据与实际试验数据相符合,将整个缸内工作过程按放热率规律分为三个阶段并分别进行研究分析.设计两种不同的燃烧室方案与原机型进行比较,讨论燃烧室喉口直径和燃烧室深度对于柴油机放热量、污染物排放量和缸内微观流场的影响.对比结果显示,当喉口直径为198 mm、燃烧室深度18.16 mm时,碳烟排放量和氮氧化物排量比喉口直径为188 mm、深度20 mm时分别下降了84.2％和43.4％;当喉口直径增加到208 mm时,缸内温度整体有所升高,氮氧化物排放量有所下降但是碳烟排放量增大.

Influence of Combustion Chamber Shape on Combustion Process in Large Power Diesel Combustion

The working process in large power diesel engine of railway locomotives was studied, and the in-cyl- inder pressure was calculated by numerical simulation which agreed well with the measured values. The com- bustion process is divided into three stages by the heat release rate curve, and each one of them is analyzed. Two different cases is proposed to compare with the original machine, and the influence of throat diameter on the combustion process is investigated by heat release case, emissions and microcosmic fields. The results indi- cate that when the throat diameter is 198 mm with a depth of 18.16 ram,Soot emission is reduced by 84.2% from the case with throat diameter of 188 mm and depth of 20 mm, and NOx emission is reduced by 43.4% with cylinder temperature declines. As throat diameter is increased to 208 ram, the temperature gets higher, and NO x emission is declined little with Soot emission is larger.