受限混合层的线性稳定性

针对超声速边界层/混合层组合流动,利用可压缩线性稳定性理论研究了流动的线性失稳特性。基本流场选取了具有不同速度特征的两股来流,采用双曲正切的混合层剖面叠加可压缩边界层自相似性解剖面构造。重点考察了混合层中心与壁面距离、对流马赫数等参数对组合流动稳定性特征的影响,其中壁面采用绝热壁面。混合层中心与壁面的距离为5~15倍的边界层厚度,混合层的对流马赫数为0.6~1.2。结果表明:该组合流动中存在独特的多重不稳定模态,并相互影响；且其不稳定模态随着壁面距离及对流马赫数的变化呈现出不同的主导行为。 

Linear stability of confined mixing layer

Linear stability analysis was utilized to investigate the stability characteristics of a supersonic boundary/mixing layer confluent flow. The basis flow was designed as a mixing layer with hyperbolic-tangent profile over a compressible boundary layer with similar solution profile. Special attention was paid to the influence of wall distance and convective Mach number on the stability of this field, of which adiabatic wall condition was used. The distance from mixing layer center to the wall ranged from 5 to 15 times boundary layer thickness, and the convective Mach number varied from 0.6 to 1.2. It was found that novel multi-unstable modes existed in the confluent flow and the dominant modes showed different manners with varying wall distance and convective Mach number.