柴油机喷孔内空化过程仿真研究

Simulation Study of Cavitation Process in Diesel Engine Injection Hole

为了更好地了解柴油机喷孔内燃油流动特性及空化现象,基于几何结构相似和空化数相似原理,采用比例放大试验装置,并结合Fluent液压仿真,分析了随入口压力的变化,喷孔内燃油空化发展规律以及该空化现象对喷孔燃油流量特性的影响。研究结果表明:固定喷孔出口压力,随着入口压力的增大,喷孔入口处将出现空化,并且空化逐步向喷孔延伸。随着入口压力的增大,孔内燃油质量流量也逐步增大。但随着孔内空化现象的出现,燃油质量增大的加速度有保持不变的趋势。

In order to better understand the fuel fl ow characteristics and cavitation phenomenon in the diesel engine nozzle,based on the principle of geometric structure similarity and cavitation number similarity,the proportional amplifi cation test device and Fluent hydraulic simulation were used to analyze the development law of fuel cavitation in the nozzle with the change of inlet pressure and the infl uence of the cavitation phenomenon on the fuel fl ow characteristics in the nozzle.The results show that,with the increase of the inlet pressure,cavitation will occur at the nozzle entrance and gradually extend to the nozzle.With the increase of inlet pressure,the mass fl ow rate of fuel in the hole also increases gradually.However,with the occurrence of cavitation in the hole,the acceleration of fuel mass increase tends to remain unchanged.