基于大涡模拟的压缩拐角激波/边界层干扰研究

Research of Shock/Boundary Layer Interactionfor a Compression Ramp Configuration Basedon Large Eddy Simulation

关键词:  激波/边界层相互干扰  可压缩湍流  大涡模拟  激波运动  G?rtler涡

Key words:  Shock wave/boundary layer interaction  Compressible turbulence  LES  Shock motion  G?rtler-like vortex

摘要:

为了提高对激波/边界层相互干扰的基本理解，采用大涡模拟(LES)对来流马赫数[Ma=2.9]，转角为24[°]的压缩拐角激波与湍流边界层相互干扰进行了研究。采用回收/调节方法作为入口湍流生成技术，并在超声速平板湍流边界层上进行了验证。采用涡识别方法和数值纹影图等流动显示方法，研究了干扰区内激波与边界层相互干扰的结构变化特征。通过对比分析湍动能和雷诺正应力在不同流向位置的分布规律，研究表明:经过激波干扰后湍动能主要集中在边界层的外层，并在拐角附近形成一个低湍动能区；雷诺正应力流向分量和法向分量在边界层内的分布呈现为单峰结构，而展向分量呈现为双峰结构。运用间歇因子对分离激波的大尺度流向运动进行研究，发现激波围绕着平均分离点作前后运动，运动的尺度等于进口湍流边界层厚度的72%。证实了拐角下游G?rtler流向涡对的存在，并对其展向分布和空间演化特性进行了详细研究。

Abstract:

In order to improve the basic understanding of shock/boundary layer interaction， a large eddy simulation (LES) was conducted to investigate shock wave and turbulent boundary layer interaction in a 24° compression ramp with a free stream Mach number of [Ma=2.9]. Recycling/Rescaling Method was used as inflow turbulence generation technique and validated on a supersonic flat plate turbulent boundary layer. Structural changes of shock system and boundary layer in the interaction region were studied by flow visualization methods such as vortex recognition and numerical schlieren. The distribution of turbulent kinetic energy and Reynolds normal stresses at different streamwise locations was compared and analyzed. The results show that turbulent kinetic energy is mainly placed in the outer of the reattached boundary layer after interaction with shock wave. A low turbulent kinetic energy region is formed near the corner. Double peak distribution of the spanwise component of Reynolds normal stresses is observed downstream of the corner， while the other components show characteristic of single peak. The large scale streamwise motion of the separation shock was analyzed by using intermittent factor. It is found that the main shock moves around the averaged separation position and the length scale is equal to 72% of inlet boundary layer thickness. The presence of G?rtler-like vortices has been confirmed. Detail investigation into the spanwise distribution and spatial evolution characteristics of these vortices was performed.