Abstract: An experimental research about the effects of external excitation on shearlayer bounding the reverse flow region was carried out.The model is a sharp leading-edgewedge like model with oscillating flap, The experimental Reynolds number is 6.67×10￣5。The inherent character of the evolution of peak frequency in shear layer bounding reverseregion for the casses with and without excitation is revealed.The response of local shearlayer to excitation is studied. The main function of excitation are to change the evol...