Properties of wall pressure beneath a transitional hypersonic boundary layer over a 7∘ half-angle blunt cone at angle of attack 6∘ are studied by Direct Numerical Simulation. The wall pressure has two distinct frequency peaks. The low-frequency peak with f≈10−50 kHz is very likely the unsteady crossflow mode based on its convection direction, i.e. along the axial direction and towards the windward symmetry ray. High-frequency peaks are roughly proportional to the local boundary layer thickness. Along the trajectories of stationary crossflow vortices, the location of intense high-frequency wall pressure moves from the bottom of trough where the boundary layer is thin to the bottom of shoulder where the boundary layer is thick. By comparing the pressure field with that inside a high-speed transitional swept-wing boundary layer dominated by the z-type secondary crossflow mode, we found that the high-frequency signal originates from the Mack mode and evolves into the secondary crossflow instability.

中文翻译：

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倾斜的直圆锥上过渡高超声速边界层下方的壁压力

通过直接数值模拟研究了在7°半角钝角锥的迎角为6°的过渡高超声速边界层下方的壁压力特性。壁压具有两个不同的频率峰值。f≈10-50kHz的低频峰很可能是基于其对流方向（即沿轴向并朝向上风对称射线）的不稳定横流模式。高频峰值与局部边界层的厚度大致成比例。沿着固定的横流涡流的轨迹，高频率高频壁压力的位置从边界层较薄的波谷底部移动到边界层较厚的肩部底部。