Separated flow noise of a flat plate at large attack angles

Abstract

Flow noise associated with separated flow of a flat plate with large attack angles was studied experimentally to obtain its acoustic characteristics and to understand its generation mechanism. The acoustic features show that the separated flow noise could be attributed to acoustic dipole sources associated with the wall-pressure fluctuations on the plate surface. The time derivative of the fluctuating wall-surface pressure is highly correlated with the associated acoustic pressure. The noise intensity source strength is proportional to the mean-square time derivative of the fluctuating surface pressure and its correlation area, being proportional to the sixth power of the oncoming flow velocity and distributed uniformly over the plate surfaces. The associated acoustic intensity is well predicted by these noise source strength distributions.