Abstract:

Tonpilz transducer head piston diameters are usually about one-half wavelength in diameter, so that ``rho-c'' radiation loading will be approximately achieved. However, for this underwater tracking application, the transducer is required to fit inside the throat of a 360-deg horn. The piston diameter is limited to 1 in., or about 0.22 wavelength at the resonance frequency, 13 kHz. The design is based on a lumped-element model. The PZT-8 ring stack is 2 in. long with an outer diameter of 0.5 in. and an inner diameter of 0.25 in. The head mass is 0.25-in.-thick aluminum, and the tail mass is tungsten, with a mass of 86 g. The transducer is isolated from its cylindrical housing with a syntactic foam spring. An O-ring piston seal is used, and a similar O-ring provides support for the tail mass. The results of free-field measurements will be presented and compared with the model, which will then be used to predict the performance after installation in the horn. [Work supported by Naval Air Systems Command.]