Mach数对高超声速旋转圆锥边界层稳定性的影响
Effect of Mach Number on Stability of Boundary Layer Over a Rotating Cone in Hypersonic Flow
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摘要: 高超声速旋转飞行器通过绕纵轴旋转获得的陀螺效应保持稳定飞行。然而，边界层转捩显著影响飞行器的飞行稳定性。旋转圆锥作为旋转飞行器的典型外形，利用线性稳定性分析(linear stability theory，LST)对高超声速流动中圆锥表面边界层线性失稳机制进行了细致研究。为了分析Mach数效应的影响机制，着重对Mach数范围5~10的线性失稳机制进行研究，选取了不同的旋转速度以区分离心诱导失稳机制。研究表明，Mach数效应对不同线性失稳机制产生不同的影响规律。最不稳定修正Mack模态、横流模态和离心模态随着Mach数增大向低频、低流向和周向波数移动，同时，最不稳定修正Mack模态、横流模态和离心模态的最大增长率随着Mach数的增大而减小。此外，证实了第2模态在旋转效应影响下本质上是斜波模态，Mach数效应减弱了第2模态波的波角。Abstract: Spinning vehicles achieve gyroscopic effects by rotating around their axis.However，transition significantly influences the stability of flight.In this work，a study of instability on the unstable modes in boundary layers over a rotating cone in hypersonic flows was presented with linear stability theory (LST).To quantify the effect of Mach number，Mach numbers 5~10 were considered，and a higher rotational velocity was considered for analysis of centrifugal mode.The influence of Mach number on different stability modes varies，which was confirmed with LST analysis.Modified Mack mode，cross-flow mode and centrifugal mode shift towards low frequency，low streamwise and circumferential wavenumbers.Also，maximum amplification rate of modified Mack mode，cross-flow mode and centrifugal mode decrease with Mach number.Meanwhile，oblique wave instinct of second mode is uncovered，and wave angle of second mode decreases with Mach number.
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