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

2aEA8. Transducer array interaction modeling using variational principles.

Harold C. Robinson

Naval Undersea Warfare Ctr., New London Detachment, New London, CT 06320

The radiation impedance acting on a pair of fluid-loaded sonar transducers is calculated using a variational principle for radiated power developed by Pierce [IEEE Trans. Ocean Eng. OE-12, 404 (1987)]. The structural motion of each transducer is approximated as a series of in-vacuo resonance modes linked via the fluid loading. These in-vacuo modes can then be utilized to determine the surface pressure on each of the transducers variationally. The normal velocities and surface pressures determined variationally are substituted into the expression for the radiated power. By separating the contributions of each structural mode to the radiated power, the mutual radiation impedances between each transducer mode can be calculated [C. H. Sherman, ``General Transducer Array Analysis,'' Cont. N00014-67-C-0424, Parke Math. Labs., Carlisle, MA (February 1970)]. Judicious summations of these contributions lead to the self and mutual radiation impedances of the transducer as a whole. Radiation impedance calculations as a function of dimensionless separation distance kd for a pair of baffled unimodal pistons and a pair of flexural disks will be presented and compared with existing theoretical predictions. [This work was sponsored by the Office of Naval Research.]