DMF/柴油RCCI燃烧碳烟生成数值模拟

Numerical Simulation of Soot Formation in DMF/Diesel RCCI Combustion

由于石油资源的短缺和汽车尾气排放的污染问题日益严重,开发内燃机可替代燃料以及新型燃烧方式,成为了当前研究领域的热点.本文以进气道喷射DMF、缸内直喷柴油,模拟研究DMF/柴油RCCI发动机碳烟生成特性.基于一台双燃料发动机,建立三维仿真模型,采用基于离散分区法的详细碳烟模型,研究DMF预混比对碳烟生成过程及颗粒粒径分布的影响规律.结果表明,随DMF预混比的增加,混合气活性降低,滞燃期增大,燃烧相位逐渐滞后,燃烧持续期逐渐增大,缸内温度降低,高温高当量比区域减小;碳烟排放总质量降低,核态颗粒物的质量和数量增加,积聚态颗粒物的质量和数量降低.

Due to the shortage of petroleum resources and the pollution of automobile exhaust emissions,the development of alternative fuels and new combustion methods for internal combustion engines has become a hot spot in the current research field.In this paper,the soot generation characteristics of DMF/diesel RCCI engine are simulated and studied by using port injection of DMF and direct injection of diesel in the cylinder.A threedimensional simulation model was established based on a dual-fuel engine.A detailed soot model based on the discrete segment method was used to study the effect of different DMF premixing ratios on soot particle generation and particle size distribution.The results showed that,with the increase of the DMF premixing ratio,the activity of the mixture decreased,both the ignition delay period and the combustion duration increased,combustion phase gradually lagged,and the cylinder temperature decreased.As the high-temperature and high-equivalent ratio area was reduced,the total amount of soot emission decreased,the mass and number of small-size particles increased,and the mass and number of large-size particles decreased.