超声速流向拐角流动稳定性分析

Stability Analysis on the Supersonic Streamwise Corner Flow

由两部件垂直装配形成的流向拐角是飞行器上常见的结构,流向拐角形成三维流动,且在试验中观测到流向拐角流动具有不稳定特性。本文采用可压缩流向拐角流动自相似解,得到Ma 4.5层流基本流。在此基础上,开展二维Bi-Global稳定性分析。稳定性分析得到了特征值谱,并发现存在两种不稳定模态,即相对较高角速度下的S系列模态和在相对较低角速度下的F系列模态,分别给出了最不稳定模态的扰动型函数。分析发现,S系列模态扰动主要在近似一维流动区域,是一维平板边界层流动Mack第二模态在角域流动中的二维延伸;而F系列不稳定模态扰动峰值在角点附近,是角域问题特有的不稳定模态。在中性曲线上,两种不稳定机制各自包围形成对应的不稳定区间。

The three-dimensional low along a streamwise corner formed by two vertically assembled plates is observed unstable.The Ma 4.5 self-similar solution is employed as the base flow and the Bi-Global stability analysis is conducted.Two series of modes are found unstable on the spectrum.The S series modes are unstable at higher angular frequency,and the the unstable F mode is found at low angular frequency.With the eigenvectors given,the unstable S series modes share the identical mechanism with the second Mach modes;the unstable mode is unique in the streamwise corner flow as its peak appears in the vicinity of the corner.Two unstable areas domainated by the unstable S and F modes exist in the neutral curve scheme.