A hypersonic inlet/isolator acts as the “compressor” for scramjet engines through a series of shocks, which induces complex internal flows. This paper comprehensively reviews the recent research achievements, focusing on the shock-dominated internal flow of an inlet/isolator. Considering the specific geometrical feature of the hypersonic inlet, the shock wave/boundary layer interactions (SWBLIs) are characterized by multiple successive shocks. Three types of couplings have been observed between adjacent interaction regions. Moreover, shock and expansion waves, which are induced by the SWBLIs and named “background wave”, are reflected in an isolator, forming a background wave/shock train interaction flow. The shock train behavior significantly differs from that in direct-connect facilities under uniform incoming flow conditions, and energy-level-transition-like phenomenon is observed when the shock train intersects with the background wave. Four types of quasi-steady background wave/shock train interactions have been reported, and three types of dynamic transitions have been observed when the shock train passes across the reflection point of the background shock. After the shock train is expelled from the internal duct, the inlet/isolator falls into unstart, and the unsteady shock-dominated flow with violent low-frequency shock oscillation occurs. A typical unstart period contains several stages, including the motion of the shock train in the isolator, large-scale separation in the inlet, and shock oscillation at the external part of the inlet. The flow mechanics of the hypersonic inlet/isolator unstart differs from that of a supersonic inlet. An unstart loop for a hypersonic inlet/isolator has been proposed, including convection wave, shock train, and acoustic wave. Once the induced factor of the unstart is removed, the unstarted shock retreats and the inlet experiences restart with the rebuilding of the supersonic flow. The restart process is highly dependent on the initial flow state and the historical effect. An instantaneous buzz arises before the unstarted shock retreats into the internal duct. Finally, the related passive (e.g., micro-vortex generator, bump, boundary layer bleed and self-circulation secondary flow control method) and active flow control methods (e.g., air jet vortex generator, plasma jet flow control, and solid-particle injection) for weakening the unfavorable impact of these shock-dominated flows are reviewed. Furthermore, the control mechanics and control effects of these flow control methods are analyzed.

高超音速入口/隔离器通过一系列冲击充当超燃冲压发动机的“压缩机”，从而引起复杂的内部流动。本文全面回顾了近年来的研究成果，重点研究了入口/隔离器的冲击主导的内部流动。考虑到高超声速入口的特定几何特征，冲击波/边界层相互作用（SWBLI）以多次连续冲击为特征。在相邻相互作用区域之间观察到三种类型的耦合。此外，由SWBLI引起的冲击波和膨胀波被称为“背景波”，在隔振器中反射，形成背景波/冲击序列相互作用流。激波列行为与均匀来流条件下的直连设施显着不同，当激波列与背景波相交时，观察到类似能级跃迁的现象。已经报道了四种类型的准稳态背景波/激波序列相互作用，并且当激波序列穿过背景激波的反射点时观察到了三种类型的动态转变。激波列从内部管道排出后，入口/隔离器陷入非启动状态，出现以激波为主的非定常流动，并伴有剧烈的低频激波振荡。典型的未启动阶段包含几个阶段，包括隔离器中激波列的运动、入口处的大规模分离以及入口外部的激波振荡。高超声速入口/隔离器未启动的流动力学与超音速入口的不同。提出了一种高超声速入口/隔离器的未启动回路，包括对流波、激波链和声波。一旦未启动的诱发因素被消除，未启动的激波就会消退，入口会随着超音速流的重建而重新启动。重启过程高度依赖于初始流程状态和历史影响。在未启动的冲击退回到内部管道之前，会产生瞬时嗡嗡声。最后，相关的被动（如微涡流发生器、凸块、边界层排气和自循环二次流量控制方法）和主动流量控制方法（如空气射流涡流发生器、等离子体射流控制和固体颗粒喷射） ）为削弱这些冲击主导的流动的不利影响进行了审查。进一步分析了这些流量控制方法的控制机理和控制效果。