燃油喷雾特性对预混合压燃氢气/柴油发动机排放影响的数值模拟研究

Numerical Simulation Research on Influences of Spray Characteristics to Emission in Hydrogen/Diesel Engine of Premixed Charge Compression Ignition

准均质压缩点火燃烧是一种新型的燃烧系统,能够同时降低碳烟和氮氧化物的排放,并且有良好的经济性。预混合压燃氢气/柴油发动机是对准均质压缩点火燃烧方式新的探索,使用改进后的KIVA-3V程序对预混合压燃氢气/柴油发动机燃烧过程进行了深入研究,分析燃油喷雾特性对预混合压燃氢气/柴油发动机排放的影响。研究发现,索特平均粒径对预混合压燃氢气/柴油发动机的排放影响很小;适当增大燃油喷雾出口速度或者喷油提前角能够使发动机排放降低;增大喷油油量,碳烟和NO的排放会增加。通过调节燃油喷雾特性参数,可以控制预混合压燃氢气/柴油发动机的燃烧过程,减少发动机的排放。

QHCCI is a new combustion mode,which may have a better economical efficiency for a high burning speed with low emissions,especially for soot and NOx.The fuel-air mixture forming and combustion process in hydrogen/diesel engine of premixed charge compression ignition is a new explore for the QHCCI mode.The KIVA-3V code is rebuilt successfully to simulate and to study the working process of the hydrogen/diesel engine,the influence of the spray characteristics to the combustion process is studied in this article.It is found that the Sauter Mean Diameter has little effects to the combustion of the hydrogen/diesel engine.The proper larger spray velocity and the advance angle would enhance the power of the engine,at the same time to reduce the let of the engine.The larger spray mass would make the cylinder pressure increased, while soot depresses and NO increase.If the spray mass is large enough,both the NO and soot would increase. Through adjusting the spray characteristics,the combustion process may be controlled,meanwhile the cylinder pressure and the let of the engine would be controlled.