Receptivity of hypersonic flow over blunt wedge under finite-amplitude disturbance wave

To investigate the receptivity characteristic of hypersonic flow under the action of free stream pulse wave, a high-order finite difference method was used to do numerical simulation of hypersonic unsteady flow over a blunt wedge with slow acoustic wave in free stream. The evolution of disturbance wave modes in boundary layer was analyzed by Fourier frequency spectral analysis. Results show that different frequency disturbance modes present different changes along streamline in boundary layer under freestream pulse disturbance. Disturbance waves in the boundary layer are mainly a fundamental mode. Ranging from the nose to the non-nose, the dominant mode shifts to high frequency rapidly; while in the region far from the nose, the shift to high frequency is very slow. In general, along the flow direction the low frequency component decreases quickly; the high frequency, especially the second harmonic mode component increases. Keen competition is accompanied by energy transformation exists among different modes in boundary layer. The dominant mode has an inhibitory action on the other modes.