The mean flow effect on the acoustic impedance of a rectangular panel

In better understanding the coupling between a vibrating panel and its surrounding acoustic medium, a precise knowledge of both the real and the imaginary parts of the radiation impedance is of critical value. The modal radiation impedance of a rectangular panel simply supported in an infinite baffle in the presence of an inviscid, uniform, subsonic flow is studied. The analysis is based on an expansion in normal modes of the transverse vibration displacement field of transforms. These are used to formulate the expressions for the modal radiation impedance, and the cross modal coupling impedance. A computer program was formulated to evaluate the modal radiation impedances. A modified Chebychev quadrature served as a major ingredient. Experiments performed were compared with the analytical results. Some experiments showed larger increases in the panel radiation resistance due to flow speed than would be predicted by the present linear theory.