Receptivity of the shear layer separating from a rear edge of flat plate

Receptivity of the laminar shear layer separating from a 90 deg. rear edge of a boundary-layer plate to acoustic disturbances is examined experimentally. The experiment is focused on the dependency of the receptivity coefficient on the rear-edge curvature as well as the frequency of acoustic disturbance. The receptivity coefficient decreases with increasing disturbance frequency for the rounded rear edge, while it is almost independent of the frequency for the sharp rear edge over the frequency range examined. A similar dependency of the receptivity on the rear-edge curvature and the disturbance frequency is obtained for wind-tunnel background turbulence. In particular, the receptivity to the fan noise impinging on the rear edge from upstream is found to be almost the same as that to the artificial acoustic disturbance coming from downstream in the present flow geometry.