Design of high‐efficiency transducer elements and arrays

Abstract

Parametric sound reception has created a need for pump transducers capable of continuous operation with intense sound fields. Reduction of internal losses and improved heat transfer become important design goals. A transducer structure has been developed in which the internal mechanical energy dissipation is reduced dramatically and the thermal coupling of the ceramic to the water is improved. The basic design consists of a quarter‐wavelength mass directly immersed in the fluid medium with the ceramic element surrounded by an air cavity and driven in quarter‐wavelength resonance. The assembly is suspended at the vibrational node by a metal flange formed integrally with the radiating mass. The resonant Q of the unloaded assembly in air can be as high as 300–400. Water loading diminishes the circuit Q to the order to 5–15 which corresponds to an effective electrical‐to‐acoustic energy conversion efficiency in the range of 85–98%. Practical elements exhibiting the same general quality of operation have been constructed over the frequency range from 7 to 400 kHz. [This research was supported by the Advanced Research Projects Agency of the Department of Defense and was monitored by the Naval Electronic Systems Command under Contract N00039‐76‐C‐0231.]