Abstract: The starting characteristics of a two-dimensional hypersonic inlet caused by the variation of freestream Mach number are numerically studied with Spalart-Allmaras turbulent model and some related experiments are conducted in a shock tunnel at two typical freestream Mach numbers of 5.5 and 5.9，respectively，for validation. The results indicate that the flow separations on the side walls combine with the separations on the bottom wall to block the inlet entry which makes the unstarted flows entirely three-dimensional. The three-dimensional flow effects should be considered in the prediction of the inlet self-starting and unstarting process. The self-starting behaviors of the inlet operated at an increasing freestream Mach number route are different from the unstarting behaviors that operated at a decreasing freestream Mach number route，which forms a hysteresis loop. When the internal concentration ratio (ICR) of the present inlet increases by 0.2，the self-starting and un-starting Mach numbers increase approximately by 1 and 0.5，respectively. The hysteresis loop enlarges and the ability to start decreases. The characteristics of self-starting and starting/un-starting dual solution area are confirmed in the shock tunnel experiments.

Key words: Hypersonic inlet；Starting characteristics；Self-starting；Hysteresis；Shock tunnel

摘要： 采用Spalart-Allmaras湍流模型对来流马赫数变化引起的二元高超声速进气道模型的起动特性进行了三维数值模拟，并在来流马赫数5.5和5.9两种工况进行了激波风洞实验验证。结果表明，进气道不起动时，模型侧板上的流动分离与外压缩面上的流动分离相融合，堵塞了进气道入口，三维流动特征显著。在预报进气道自起动和不起动时，应当考虑三维流动效应。逐步增大来流马赫数和逐步减小来流马赫数两种路径下，进气道存在起动迟滞现象。对于本文的进气道模型，当内收缩比增大0.2时，自起动马赫数约升高1，不起动马赫数约升高0.5，进气道的起动迟滞环变大，起动性能下降。在激波风洞中获得的进气道自起动以及起动/不起动双解区的实验结果与数值模拟相符合。

关键词: 高超声速进气道；起动特性；自起动；迟滞；激波风洞