Acoustic Refraction and Scattering with Compliant Elements. I. Measurements in Water

Abstract

The velocity of sound in water may be reduced markedly with mechanical structures which effectively increase the compressibility of water. A compliant tube, formed from commercially available round tubing by deforming its cross section elliptically, is a simple example of such a structure. Compliant tubes are useful in the design of lenses at frequencies below the lowest flexural resonant frequency of a compliant tube immersed in water and reflectors for frequencies up to where the spacing between adjacent compliant tubes corresponds to a half-wavelength. Several measuring techniques were utilized to demonstrate the different aspects of compliant tubes under various conditions of interest. The analytical generalizations due to these measurements will be discussed in a second article.