二维激波与剪切层相互作用的直接数值模拟研究

DIRECT NUMERICAL SIMULATION OF THE INTERACTION OF 2D SHOCK WAVE AND SHEAR LAYER

采用五阶weighed esseritially non-oscillatory(WENO)格式和三阶total variation diminishing(TVD)Runge--Kutta格式,通过求解二维非定常Navier--Stokes方程,直接数值模拟了激波与剪切层相互作用,目的在于揭示激波与剪切层相互作用过程中噪声产生的机理.研究发现:(1)当入射激波穿过剪切层时,剪切层中心位置向下层区域偏移;(2)入射激波穿过剪切层产生小激波,在小激波与剪切层接触点处产生声波并向外辐射;(3)反射激波穿过剪切层后形成了分段弧状激波;(4)当反射激波穿过剪切层时,激波在鞍点处泄漏并向外辐射声波,这是一种激波泄漏机制.

Direct numerical simulation （DNS） of the interaction of shock wave and shear layer was performed. The com- pressible unsteady two-dimensional Navier-Stokes equations were solved using the fifth-order WENO scheme combined with the third-order TVD Runge-Kutta scheme. The purpose of this paper is to reveal the mechanism of sound generation in the interaction of shock wave and shear layer. The results show that： （1） When incident shock wave is passing through the shear layer, the center of the vortex cores is shifted towards the lower side; （2） The interaction of incident shock wave and shear layer generates shocklet, and then acoustic wave is generated and radiated at the locus of contact of shocklet and shear layer; （3） Several arc-shocks are formed after reflected shock wave passing through shear layer; （4） When re- flected shock wave is passing through shear layer, shock wave is leaking in the braid region and shock-associated noise is generated at the saddle points between vortices. This is a form of shock leakage mechanism.