论文标题
大扫式马赫数
Hypersonic attachment-line instabilities with large sweep Mach numbers
论文作者
论文摘要
这项研究旨在阐明具有较大扫扫数的高超音速依恋线不稳定性。研究了高度扫掠的流动，从而研究了引起大量扫掠马赫数的流动。高保真基础流是通过使用高阶减震方法求解完整的Navier-Stokes方程来获得的。使用局部和全球稳定理论，发现沿前缘的层流驱动过渡是依赖固定线模式，这与实验性观察Gaillard1999非常吻合。这种模式的行为解释了由于扫描马赫数高于5的过渡而发生过渡的原因。此外，如果用边界层假设计算基本流量，则不存在此附件线模式，这表明在边界层外部不忽略边界流的影响是正常完成的。可以清楚地证明，全局模式显示了两个附件模式的特征，例如在扫描Hiemenz流中，以及沿表面下游的跨流式模式。与不可压缩的流相反，该模式显示为无粘性的性质。此外，前沿曲率对大跨度波数的固定线模式具有不稳定的效果，但对于小跨度波数的稳定效果。
This study aims to shed light on hypersonic attachment-line instabilities with large sweep Mach numbers. Highly swept flows over a cold cylinder that give rise to large sweep Mach numbers are studied. High fidelity base flows are obtained by solving full Navier-Stokes equations with a high-order shock-fitting method. Using local and global stability theories, an attachment-line mode is found to be dominant for the laminar-turbulent transition along the leading edge that agrees well with experimental observations Gaillard1999. The behavior of this mode explains the reason why the transition occurs earlier as the sweep Mach number is above 5. Also, this attachment-line mode is absent if the base flow is calculated with boundary-layer assumptions, indicating that the influence of inviscid flow outside the boundary layer can not be ignored as is normally done. It is clearly demonstrated that the global modes display the features of both attachment-line modes, as in sweep Hiemenz flow, and cross-flow-like modes further downstream along the surface. In contrast to incompressible flows, the mode is shown to be of inviscid nature. Moreover, the leading-edge curvature has a destabilizing effect on the attachment-line mode for large spanwise wave numbers but a stabilizing effect for small spanwise wave numbers.
