Numerical investigation on behaviors of shock train in a hypersonic inlet with translating cowl

In order to extend the range of flight Mach numbers, the variable-geometry inlet equipped with a translating cowl has been proposed. To estimate the effects that the translation of cowl has on the behavior of shock train under constant backpressure in a two-ramp hypersonic inlet, numerical investigations utilizing dynamic mesh method have been conducted. The structures of background waves and trajectories of shock-impact points with variable internal contraction ratios at Mach number 5.9 are obtained. Then, the paths of shock train leading edges have been provided and studied. The results reveal that the shock train leading edge on the bottom wall crosses the shock-impact points abruptly, which forces the shock train to undergo multiple back-and-forth translation motions accompanied with separation mode transition. Severe abrupt motions of shock train occur when it encounters multiple shock-impact points aroused by the separation bubble. Analogously, the shock train interacts with the separation bubble located on the top wall periodically. The probability that the oscillation takes place is increased due to the existence of separation bubble. Therefore, the behavior of shock train is highly associated with the variable background waves.