喷油定时对柴油机超多喷孔预混合燃烧影响研究

Effect Investigation of Fuel Injection Timing on Premixed Combustion in DieselEngine with Ultramultihole Nozzle

柴油机低温预混合燃烧能够同时大幅度降低NOx和碳烟(soot)排放,本研究采用大量废气再循环(EGR)实现低温燃烧来降低NOx排放,采用超多喷孔喷油嘴并结合高压喷射来缩短喷油持续期,实现预混合燃烧从而降低soot排放,主要对喷油定时如何影响柴油机超多喷孔预混合燃烧性能进行了试验研究,选定4个试验工况,通过改变喷油定时来测试柴油机性能,结果显示随着喷油始点从上止点前向后推迟,各工况的NOx和soot排放都有不同程度的同时下降,有别于传统燃烧方式,但HC,CO,比油耗(BSFC)有所升高。

The low-temperature premixed combustion can simultaneously reduce NOx and soot emissions in diesel engines.This research uses a heavy EGR to achieve the low temperature combustion in order to reduce NOx emissions.Moreover,it is necessary for combining an ultramultihole(UMH) nozzle and a high injection pressure to shorten injection duration to achieve the premixed combustion in order to reduce soot emissions.The purpose of this study is mainly to investigate the effect of the injection timing on the premixed combustion of a test diesel engine in four selected test cases.Results showed that NOx and soot emissions all have a reduction with the retarding of the fuel injection timing.However,HC,CO and BSFC have a slight increase.