Numerical Investigation of 2-D Hypersonic Inlet Starting Characteristic Caused by Dynamic Angle-of-Attack

In the flight, hypersonic vehicle goes through different kinds of flight status, experiencing various of disturbances. If control system fails to adjust the pose of vehicle, the pitching, yawing and rolling attitude could be transformed or forced to oscillate transiently, then the dynamic of angle-of-attack can not be avoided. It’s a question whether hypersonic inlet would keep start and how the performances change. In this paper, unsteady CFD simulation is performed on 2-D hypersonic inlet at Mach 4.03. Effect of dynamic angle-ofattack on starting characteristic is analyzed. The investigation suggests that: The appearance, development and disappearance of low mach number region near solid wall is affected notablely, which would alter the aerodynamic characteristic of inlet. For the dynamic increasing of angle-of-attack, characteristics of flow field and performances of inlet are significantly altered, unsteady flow field features and the performances are lag behind of the steady case. For the oscillating motion, the value of unstarting angle-of-attack increase and restarting value decrease with the rising of reduced frequencies. It is predicted that when the reduced frequency reaches a critical value, depending on the initial angle-ofattack, the hypersonic inlet would keep start/unstart in the whole circle.