AN EXPERIMENTAL INVESTIGATION OF GAS-DRIVEN UNDERWATER SOUND DEVICES

A number of concepts for generating underwater acoustic signals using the energy in chemical propellants were studied. Two of the more promising, a valved gas device and a vortex whistle, were singled out for experimental investigation. The valved gas device,named the Gas Actuated Sonar Pulser (GASP), could be used either as a diaphragm-type unit or as a device for pulsing pressurized gas directly into the water. The vortex whistle, an extremely simple device, produces a tone whose frequency is proportional to the flow rate of working fluid passing through the system. Data were obtained on wide-band acoustic pressures and signal spectral content as functions of operating gas pressures for both devices. In these tests, the propellant gases were simulated with compressed nitrogen. Directionality tests were also run on the vortex whistle. In both devices the signal quality was not very good and efficiencies were very low. For a cheap, expendable unit, however, the vortex whistle might prove to be quite useful. (Author)