ASA 127th Meeting M.I.T. 1994 June 6-10

2aEA9. On acoustic coupling of flextensional sonar projectors to vibration of nearby structures.

Khushi L. Chandiramani

Neal A. Brown

Atlantic Appl. Res. Corp., 4 A St., Burlington, MA 01803

The fundamental mode shape of a flextensional sonar projector, effective in transmission as well as reception, is such that while the central portions of the transducer, close to the minor axis of its elliptical cross section, are moving outward, the end segments, close to the major axis, are moving inward. This feature introduces a quadrupole component of radiation and reception to the transducer, along with a related enhancement of the high-wave number content of the radiated near field and the minor lobe receiving sensitivity. Effects of these changes are assessed on (i) increased resonant vibration of surrounding plate-like structures when the transducer is radiating, and (ii) increased flow-noise response of the transducer when receiving while on a moving platform. [Work supported by Naval Undersea Warfare Center under sponsorship of Office of Naval Research.]