On the vibro-acoustic response of a cylindrical shell submerged near a free sea surface

Abstract

A vibro-acoustic model of a structurally excited cylindrical shell of infinite length submerged in a heavy fluid at a finite distance from a free surface is presented. Expressions for the shell displacement, the acoustic pressure in the interior cavity of the shell and the acoustic pressure at all field locations in the exterior domain are analytically derived. The formulation for the exterior acoustic pressure is developed using the image method and Graf's addition theorem. Results for the structural and acoustic responses of the cylindrical shell submerged at a finite distance from the free surface and in an unbounded fluid domain are compared. The effects of the shell circumferential modes, interior cavity resonances and proximity of the free surface on the shell acoustic responses are examined. New mechanisms influencing the low frequency vibro-acoustic response of a submerged hull near a fluid boundary are described.