Abstract The supersonic/hypersonic flow through an aircraft intake must be decelerated before entering the combustion chamber to ensure efficient combustion. Retardation in the flow speed is achieved through a progression of oblique and normal shock waves in the isolator region of the intake. However, the advantages of speed reduction in intake are usually accompanied by huge losses due to the shock wave and boundary-layer interactions (SBLIs). These losses may include, inlet-unstart, abrupt thickening or separation of the boundary layer, unsteady shock oscillations, etc. Clearly, the SBLIs must be controlled to minimize the losses and improve the performance of the complete vehicle. Control of these interactions by manipulating the strength of the shock using a shallow cavity with wall ventilation has gained prominence. In this study, the efficacy of a thin porous surface deployed over shallow cavity in the higher adverse pressure gradient regions of Mach 5.7 and Mach 7.9 mixed-compression intakes, is experimentally investigated. With the variation of diameter and pitch of the pores, the porosity in Mach 5.7 intake is varied as; 4.5%, 7.5%, 17%, 21.6%, and 25%. A maximum of 20.53% drop in static pressure in the Mach 5.7 intake controlled by the cavity covered with 25% surface perforation, at a near-reattachment location ( x / L = 0.73), is observed. However, the separation bubble in Mach 5.7 intake is suppressed most efficiently, when the cavity is covered with 17% porous surface. For Mach 7.9 intake also, the 25% surface perforation has maintained its superiority in reducing the wall static pressure to a maximum of 20.20% at x / L = 0.73. Once again, the 17% porous surface controlled configuration is found to be quite effective in suppressing the bubble. A qualitative investigation of the Schlieren images supports the findings of wall static pressure data. Graphic Abstract

中文翻译：

---

多孔表面覆盖的空腔在控制高超声速进气中的冲击/边界层相互作用中的评估

摘要 通过飞机进气口的超音速/高超音速气流在进入燃烧室之前必须减速，以确保有效燃烧。流速的延迟是通过在进气口的隔离区中倾斜和垂直冲击波的进展来实现的。然而，由于冲击波和边界层相互作用（SBLI），进气速度降低的优势通常伴随着巨大的损失。这些损失可能包括入口未启动、边界层的突然增厚或分离、不稳定的冲击振荡等。显然，必须控制 SBLI 以最大限度地减少损失并提高整车的性能。通过使用带有墙壁通风的浅空腔来操纵冲击强度来控制这些相互作用已经变得突出。在这项研究中，实验研究了在 5.7 马赫和 7.9 马赫混合压缩进气道的较高不利压力梯度区域中部署在浅腔上的薄多孔表面的功效。随着孔隙直径和节距的变化，5.7马赫进气道的孔隙度变化为：4.5%、7.5%、17%、21.6% 和 25%。观察到由覆盖有 25% 表面穿孔的空腔控制的 5.7 马赫进气道的静压最大下降 20.53%，在接近再附着的位置 (x / L = 0.73)。然而，当空腔被 17% 的多孔表面覆盖时，5.7 马赫进气中的分离气泡被最有效地抑制。对于 7.9 马赫的进气道，25% 的表面穿孔保持了其在将壁面静压降低至 x / L = 0.73 时最大 20.20% 的优势。再来一次，发现 17% 多孔表面受控配置在抑制气泡方面非常有效。纹影图像的定性研究支持壁静压数据的发现。图形摘要