Investigation of a rupture-induced underwater sound source

Abstract

Underwater acoustic experiments, surveys, and sonar often require a repeatable, predictable, and broadband sound source. In many instances, a high amplitude, impulsive sound source is utilized to produce a broad-band event capable of penetrating the seabed and propagating to long range. Prior experimentation at the Applied Research Laboratories at the University of Texas at Austin (ARL:UT) has demonstrated the viability of a device that utilizes a rupture disk as an underwater acoustic source. A rupture disk is an expendable diaphragm used in industrial applications, which is designed to break at a specified pressure differential. Placing a rupture disk over an evacuated chamber and mechanically breaking the disk (either by striking on demand or via hydrostatic pressure) at a specified depth was demonstrated to produce high-amplitude, broadband waveforms as the cavity collapses and inflowing water impacts the bottom of the chamber. Residual bubble oscillations are greatly reduced due to the fact that the collapse chamber is initially evacuated. This source also has the advantage that it is solely comprises inert materials—no explosives or combustive gases are required. Discussion will focus on new and expanded source level measurements and preliminary comparisons to model predictions.