中文摘要：

应用三维CFD商用模拟软件FIRE对车用共轨柴油机在高负荷工况下采用近后喷射策略的缸内工作过程进行数值计算，分析后喷量和主、后间隔角对有害排放物生成的影响．结果表明，随后喷量和主、后间隔角的增加，NOx的生成量显著减少，而经济性有所恶化；同时，近后喷射还是降低柴油机碳烟排放的一种非常有效的手段，适当的近后喷射一方面能对缸内流场造成较大的扰动，另一方面能使后喷燃油主要在富氧区域内形成燃油蒸气，从而明显减少碳烟的生成量．采用近后喷射能取得比原机更好的NOx、碳炯和平均指示压力三者的折中性能，并且在后喷量为10％～21％、主、后间隔为10°～18°CA区间选取近后喷射参数能获得较优的折中性能.

英文摘要：

Numerical simulation of thermodynamic cycle and combustion ofa turbocharged vehicle diesel engine with closed post injections under high load operations was carried out by means of a CFD tri-dimensional numerical analysis software FIRE. In this paper, the effects of closed post injection fuel quantity and interval between post and main injection on combustion process were discussed. The computed results indicated that with the increasing interval and post injection fuel quantity, the generation of NOx was evidently reduced, while the fuel economy had worsened. At the same time, the post injection technology is a very effective means to reduce soot emissions. The appropriate post injection parameters could, on the one hand, reinforce the disturbance effect of in-cylinder flow field; on the other hand, post injection fuel could form fuel vapor mainly in the oxygen-enriched region, thus obviously reducing the generation of soot. Better compromise performance of the indicated mean pressure, NOx and soot could be achieved by using post injection than by the original machine. Even better performance could be achieved when post injection mass is 10%-21% and the main and post injection interval is 10°-18° CA.