### 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.