Abstract: On the purpose of giving insight into the motion law，factors and self-sustained mechanism of the large-scale separation zone in the inlet start process，the accelerating start process of simplified 2-dimensional hypersonic inlet were investigated. The startability，start process and motion law of separation zone of different cowl angle configurations were compared，and the flow mechanism was analyzed. The results reveal that: (1)The startability of 2-dimensional upper wall one-side compression inlet is influenced by the cowl angle significantly. With the cowl angle increasing from 0° to 12°，the start Mach number shows a trend in which it decreases first and then increases，reaching a minimum at 4°.(2)Large-scale separation zone exists in all cowl angle configurations in unstart status. The upstream half of the separation zones are nearly the same，while the downstream halves are distinctly different.(3)In the accelerating start process，the separation zones sustain itself mainly depending on the reflection shock of separation shock at the upper wall. At the same incoming flow Mach number，the strength of the reflection shock of separation shock at the upper wall of different cowl angle configurations is different，which influences the self-sustained ability of the separation zone so as to influence the startability.

Key words: Hypersonic；Inlet；Start process；Internal duct；Separation zone

摘要： 为深入了解大规模分离区在进气道启动过程中的变化规律、影响因素及自持机理，针对简化的二维高超声速进气道加速启动过程进行了数值研究，对比了不同唇口角构型的启动性能、启动过程和分离区变化规律，分析了其中的流动机理。结果表明:(1)上壁面单侧压缩的二维进气道启动性能受唇口角影响显著，随着唇口角从0°增加到12°，启动马赫数呈现先减小后增加的趋势，4°时启动马赫数最小。(2)不同唇口角构型不启动状态都存在大规模分离区，分离区的前半部分接近一致，后半部分差异明显。(3)在加速启动过程中，分离区主要依靠分离激波在上壁面的反射激波维持自身的存在，不同的唇口角构型在相同来流马赫数下分离激波在上壁面的反射激波强度不同，这影响了分离区的自持能力，从而影响了启动性能。

关键词: 高超声速；进气道；启动过程；内收缩段；分离区