Scattering from internally complex finite shell models

Abstract

Data on acoustic scattering from finite-length internally loaded circularly cylindrical models were obtained with use of a water tank facility at the Naval Research Laboratory. Analysis of these data in the mid-frequency range (2<ka<12, where k is the acoustic wave number and a the cylinder radius) reveal three important regions of scattering phenomena: the bow/stern aspect (in a spherical coordinate system, within a polar angle of about 20°), the helical wave aspect (within about 45° to 85°), and the beam aspect (within about 85° to 90°). The models studied were closely symmetric around the polar axis and also with respect to the plane defined by the polar angle of 90°. There will be a review of the underlying physical mechanisms in these scattering regions as affected by the shell and its endcaps, by the internal deep rings (frames), and by additional internal structures mounted to the rings. [Work supported by ONR.]