Scattering of Acoustic Energy by Solid and Air-Filled Cylinders in Water

Abstract

This paper presents the results of an experimental investigation of the scattering of acoustic energy from finite circular cylinders in water. Solid and hollow brass cylinders were used as targets. Distribution-in-angle diagrams of acoustic energy scattered in the plane perpendicular to the longitudinal axis of the cylinders are shown for changes in finite cylinder length, changes in pulse length, and changes in frequency. Pulse photographs are presented to describe the echo structure of solid and hollow cylinders. Photographs are shown of the pulses scattered in the backward direction in the plane normal to the longitudinal axis of the cylinder and in the plane containing the longitudinal axis of the cylinder. The change in echo structure is presented as a function of pulse length and frequency. The echo structure exhibits characteristics dependent upon the sharp corners of the cylinder where there is a large change in slope and a discontinuity between brass and water. The photographs of pulses returned from the cylinders in the plane normal to the longitudinal axis describe the existence of surface waves which travel around the circumferences of the cylinders. (This work was partially supported by the Bureau of Ships.)