不可压缩空腔流的振荡模式

THE OSCILLATION MODE OF INCOMPRESSIBLE CAVITY FLOW

采用二维大涡模拟方法进行了空腔水流场的数值计算,考察空腔前缘动量损失厚度及来流速度等因素如何影响空腔流的振荡,同时考察了空腔长深比与空腔流振荡模式的关系.用空腔水流场的粒子图像测速测量结果验证了数值计算的可信性.结果表明,空腔水流是否发生振荡取决于壁面摩擦速度.瞬时涡结构和空腔阻力系数2个方面的特征显示空腔水流场有2种典型的振荡模式,剪切层模式与尾流模式,确定振荡模式的关键因素是空腔长深比.

The numerical calculation of the cavity flow using 2D-LES method has been conducted to examine how the momentum loss thickness and inflow velocity at the cavity leading edge affect the cavity flow oscillations, and how the length-to-depth ratio of the cavity is related to the oscillation modes of the cavity flow. PIV measurements of cavity flows verify the credibility of the results of numerical calculation. The results show that the friction velocity determines whether or not the flow of water over the cavity will oscillate, The instantaneous vortex structures and the cavity drag coefficients identify two typical modes of oscillation, the shear layer mode and wake mode. The key factor that determines the oscillation mode is the length-to-depth ratio of the cavity.