剪切来流下超空泡射弹空化与水动力特性的数值研究

为研究剪切来流下超空泡射弹空化与水动力特性,采用Mixture多相流模型、Schnerr and Sauer空化模型和Realizable k-ε湍流模型,对水下剪切来流中的超空泡射弹进行数值模拟研究,来流平均速度为600 m/s,剪切率为0～7 500 s^-1。均匀来流中,包裹射弹的超空泡上下对称,阻力以压差阻力为主,升力系数为0。剪切来流下,超空泡不对称,并向低速侧偏斜,压差阻力略微增加,致使阻力系数增大。由于高速侧绕流更快,低速侧的涡旋产生更显著的卷吸作用,使得射弹受到朝向低速侧法向黏性力的作用,升力系数减小为负值。当剪切率进一步增大时,弹肩高速侧出现沾湿,弹体周围黏度增加,导致阻力系数显著增加,且水压显著大于饱和蒸汽压,压力的法向分量更加剧烈地作用到低速侧方向,升力系数进一步减小。

Numerical Simulation of Cavitation and Hydrodynamic Characteristicsof Supercavitating Projectile in Shear Flow

In order to study the cavitation and hydrodynamic characteristics of supercavitating projectile in shear flow,the Mixture multiphase model,Schnerr-Sauer cavitation model and Realizable k-ε turbulence model were used to simulate the underwater supercavitating projectile in shear flow. The inflow average velocity was 600 m/s,and the shear rates range from 0 to 7 500 s^-1. In the uniform flow,the supercavity surrounding the projectile is symmetrical. The drag is dominated by pressure drag,and the lift coefficient is 0. In the shear flow,the supercavity is asymmetric and deviates towards the low-speed side. Besides,the pressure drag increases slightly,leading to the increment of the drag coefficient. Because the flow around the high-speed side is faster,the vortex at the low-speed side produces a more significant entrainment effect,which makes the projectile suffer from the normal viscous force orientating towards the low-speed side,and the lift coefficient becomes negative. When the shear rate increases further,the shoulder on the high-speed side contacts the water. The viscosity around the projectile increases,resulting in a significant increase in the drag coefficient. The water pressure is substantially greater than the saturated steam pressure,and the normal component of pressure acts more strongly towards the low-speed side,resulting in the further decrement of the lift coefficient.