机翼跨声速抖振数值模拟及模态分析

绕机翼的跨声速抖振流动是典型的复杂不稳定流动，对其非定常特性及失稳机制的研究具有重要的工程和学术价值。通过非定常雷诺平均Navier-Stokes（URANS）仿真方法和动模态分解（DMD）分析手段，研究了CRM（Common Research Model）等典型机翼的跨声速抖振流动特性及其主要失稳模态。数值仿真结果表明机翼的跨声速抖振表现为多失稳模式下的宽频特性。除了激波的弦向失稳，还会伴随发生激波的展向失稳，它们都表现为低频特性。翼梢处的高频响应可能是由激波诱导的低频失稳与翼尖涡相互耦合形成。DMD分析结果显示机翼展长和后掠因素诱导了激波展向失稳模态。本研究对抖振流动的物理建模、控制及理解相关的气动弹性现象具有指导意义。

Numerical simulation and modal analysis of transonic buffet flow over wings

Transonic buffet flow over a wing is a classical complex and unstable flow case, and the research on unsteady characteristics and instability mechanism has significant engineering and academic values. By means of numerical simulation and Dynamic Mode Decomposition (DMD) analysis, this paper studies the characteristics and the dominant modes of buffet flow over wings, such as CRM (Common Research Model) wing. The results by the Unsteady Reynolds Averaged Navier-Stokes (URANS)method indicate that the 3-D transonic buffet flow is dominated by multiple instability patterns with broadband spectrum. Besides the shock oscillation along the chordwise, the spanwise oscillation is also occurred, which both display in low-frequency manners. While the high-frequency response at the wingtip may be caused by the coupling of oscillating shock and K-H type instability, the results from DMD modes show that the factors of sweep and aspect ratio result in the spanwise instability of the shock. This study has potential meaning to perform physical modeling, control and to understand complex aeroelastic phenomena associated with transonic buffet flow.