ASA 125th Meeting Ottawa 1993 May

3aSA2. Mean flow effects on the vibroacoustic behavior of baffled plates in heavy fluids.

Franck Sgard

G.A.U.S, Genie Mecanique, Univ. of Sherbrooke, Sherbrooke, PQ J1K 2R1, Canada

Noureddine Atalla

University of Sherbrooke, Sherbrooke, PQ J1K 2R1, Canada

The originality of the present paper lies on the development of a formulation accounting for mean flow effects in the vibroacoustic model of a baffled plate. The importance of those effects on the vibrational behavior and stability of a baffled plate with arbitrary boundary conditions, as well as its acoustic radiation pattern, is assessed. The analysis is based on a finite-element method for the calculation of the plate transverse vibrations and the use of the extended Kirchhoff's integral equation to account for fluid loading with mean flow. A boundary-element method is used to compute the acoustic radiation impedance. The formulation shows explicitly the effects of mean flow in terms of added mass, stiffness, and radiation damping. Furthermore, the added stiffness is shown to be responsible for the instabilities that occur as the flow speed increases. Details of the formulation as well as its numerical implementation are exposed and results showing the effect of the mean flow on the different vibroacoustic indicators (mean square velocity, radiated acoustic power, modal radiation efficiencies) are presented.