Path dependence characteristic of shock train in a 2D hypersonic inlet with variable background waves

The inlet equipped with a translating cowl is confirmed to have the ability of extending the range of flight Mach numbers. Along with the translation of cowl, the performance of inlet and background waves in the isolator vary continuously. Up to now, the behavior of shock train in opposite directions of translating cowl is still unknown. Numerical investigations have been conducted to study the path dependence characteristic of shock train with the application of dynamic mesh method. Based on the paths of shock train leading edges, it is discovered that the behavior of shock train is highly related to the variable background waves. Furthermore, the results reveal that the path dependence characteristic apparently embodies in the abrupt motions, average velocities of shock train, structures of shock train and oscillations. It is the discrepancies of critical internal contraction ratios, which the abrupt motions occur at, that lead to the hysteresis loops in the paths of shock train leading edges. In each hysteresis loop, the structures and average velocities of shock train in opposite directions of translating cowl are different. Meanwhile, the shock train would oscillate around the separation bubble, which intensifies the unsteadiness of shock train behavior. With the cowl moving upstream, the peak frequency of oscillation and the range of internal contraction ratio that oscillation takes place in are larger than the results obtained in the reverse direction. (C) 2019 Elsevier Masson SAS. All rights reserved.