关键词: 高超声速进气道；起动特性；自起动；迟滞；激波风洞

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