ASA 127th Meeting M.I.T. 1994 June 6-10

3pSAa5. Modal radiation from a nonbaffled rotating circular plate in light fluid medium.

Olivier Beslin

Jean Nicolas

G.A.U.S., Mech. Eng. Dept., Univ. de Sherbrooke, Sherbrooke, PQ J1K 2R1, Canada

A circular plate vibrating on resonance and rotating with a uniform angular speed is considered. In a moving frame (rotating with the plate), the plate motion can be expressed as the superposition of two propagating circular waves, traveling in opposite angular directions and having the same angular wave number and angular frequency. In a fixed frame (relative to the surrounding medium), the plate motion is still seen as two propagating circular waves, having the same angular wave number as in the moving frame. However they have two different angular frequencies, depending on the rotating speed. The modal radiation of a rotating plate can then be expressed in terms of radiation from propagating circular waves that allow a better understanding of the physical phenomena induced by the rotation. Radiation from propagating circular wave is computed using an integral formulation: The acoustical velocity is imposed on the plate area. The jump of pressure across the plate area is computed using a discretization method based on an approach proposed by Filipi [J. Sound Vib. 54(4), 473--500]. The influence of the rotating speed of the plate and the angular wave number of the mode on the radiation factor is discussed.