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在一台涡轮增压直喷式柴油机上研究了预喷射对柴油机燃烧的影响。在改变预喷射油量和定时的情况下,测定了各种喷油条件下的发动机排放。结果表明,预喷射能减少低负荷时的NO_x和总HC排放,并能在一定程度上改善燃油耗。为了解这一现象,对柴油机的燃烧进行了分析,并用内窥镜观察了燃烧过程。发现预喷射之所以能降低燃气平均温度是由于限制了预混合燃烧以及延缓扩散燃烧的缘故。摄取了预喷射燃烧产生的燃气被喷入预喷射燃烧火焰中的主喷射油束卷吸而导致燃烧延缓的照片。
The effect of pre-injection on the combustion of a diesel engine was studied on a turbocharged direct injection diesel engine. Engine emissions under various fuel injection conditions were measured with varying pre-injection quantity and timing. The results show that pre-injection can reduce NO x and total HC emissions under low load, and can improve fuel consumption to a certain extent. In order to understand this phenomenon, the combustion of the diesel engine was analyzed and the combustion process was observed with the endoscope. Found that the reason why the pre-injection can reduce the average gas temperature is due to the limited pre-mixed combustion and delayed diffusion combustion. Ingestion of pre-injection combustion gas is injected into the pre-injection flame combustion of the main jet fuel bundle entrapment caused by the delay in the photo.