垂直多孔喷嘴内部流动空穴现象数值模拟分析

Numerical Simulation and Analysis of Cavitating Phenomena in a Vertical Multi-hole Nozzle

柴油机喷嘴内部空穴流动是影响喷雾特性的重要因素,在对柴油机喷嘴喷孔内部空穴流动现象分析的基础上,利用混合多相流空穴模型对垂直多孔喷嘴完全发展了的空穴流动进行了三维数值模拟,分析了喷油压力、气缸背压及喷孔入口圆角半径与喷孔倾角对喷孔内部空穴分布的影响。验证了低空穴参数对应的空穴层延伸长度较长,喷孔入口锐边过渡会增加喷孔出口液流紊乱,从而加速雾化。

The cavitating flow in a nozzle hole is a very important factor to affect diesel fuel spray characteristics. The cavitating flow phenomena in the diesel injection nozzles was analyzed. Based on this, using mixture multi phase cavitating flow model, 3-D numerical simulation was done to the fully developed cavitating flow in nozzle holes of a vertical multi-hole injector, the effects of injection pressure, back pressure, turning angle of the orifice and hole inclination angle on the cavitation phenomena in nozzle holes were analyzed. The results validated that the lower cavitation parameter was, the longer extending length of cavitation film could be, exit flow of holes with sharp-edged entrance shape would be more turbulent to accelerate the break up of spray accordingly.