喷油嘴结构对尾喷雾化质量影响的研究

Effects of Nozzle Structure on Spray Atomization at End of Injection

利用高速频闪照相系统研究了不同的喷油嘴结构参数对燃油尾喷雾化质量的影响。试验结果表明,喷油嘴压力室容积是影响尾喷雾化质量的关键因素。传统的有压力室喷油嘴在尾喷后期有少量燃油以较低的速度呈液滴状流出喷孔,完全没有雾化;而对于无压力室喷油嘴,针阀落座时燃油喷射过程能迅速停止,未出现尾喷后期雾化质量不良的现象。据此推论,无压力室喷油嘴使柴油机HC排放降低的一个重要原因是消除或减轻了有压力室喷油嘴所存在的尾喷雾化质量不良现象。

By using high speed camera, the effects of nozzle structure on the spray atomization at the end of injection are investigated in this paper. The experimental results show that, after injection of a sac nozzle, there is still a little of fuel flow from orifices as liquid in a very low speed without atomization. On the contrary, the fuel injection process stops immediately right after the valve covers orifices, and there is no more liquid fuel flowing out. Spray atomization at the end of injection is one of the key factors about why the HC emission from a diesel engine as using VCO nozzle is much lower than that using normal sac nozzle.