柴油机喷嘴空穴流动特性分析

Cavitating Flow Characteristics in Diesel Nozzle

利用混合多相流空穴模型进行了喷嘴内气液两相流动的数值模拟。分析了喷油压力、背压、喷嘴几何特征参数对喷孔内空穴流动、空穴区域分布的影响,以及各种参数对流量系数和燃油出口平均速度的影响。研究结果表明,无量纲空穴数直接影响喷孔内的空穴分布,而流量系数和燃油出口平均速度等流动特性则与喷油压力、喷孔入口圆角半径、喷孔倾角、针阀升程等几何特征参数有很大关系。

With the mixed multi phase cavitating flow model, the gas and liquid two-phase flow in the nozzle was simulated. The influences of injection pressure, back pressure and nozzle geometry characteristics on cavitating flow and distribution inside the nozzle were analyzed. Also, the influences of various parameters on discharge coefficient and average fuel exit speed were analyzed. The results show that the nondimensional cavitation parameter influences directly on cavity distribution in the nozzle. In addition, the injection pressure, nozzle entrance radius, nozzle obliquity and needle valve lift have great relationship with discharge coefficient and average fuel exit speed.