An experimental study of the acoustic oscillations by flows over cavities

Abstract : We present an experimental study of acoustic oscillations induced by an internal airflow over a shallow and a deep cavity. The Kelvin-Helmholtz instability is interacting with an acoustic mode of the cavity or of the duct, leading to a resonance which produces a very high sound level. The influence of upstream boundary layer thickness and neck thickness is studied. Some results obtained by modifying the upstream lip shape, by crenel addition, are also given. © 2004 by ASME.