ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

2pEA10. Variational model for the radiation impedance of class IV transducers II.

Harold C. Robinson

Elizabeth A. McLaughlin

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

In a previous paper [H. C. Robinson and E. A. McLaughlin, 3318(A) (1994)], the variational method of determining modal radiation impedances was applied to a pair of class IV transducers. The self- and mutual radiation impedances for the quadrupole, octopole, and monopole modes were presented. This paper extends the analysis to include the effects of other asymmetric modes of the class IV. The in-vacuo mode description of the transducer's surface velocity will be improved by using three-dimensional mode shapes. The trial functions describing the surface pressure are modified as well. Changes in the impedance characteristics for the symmetric modes due to this improved transducer description will be shown. The characteristics of the nonsymmetric modal impedances are compared to those of the symmetric modes as a function of dimensionless major axis ka and dimensionless separation distance kd. Suitable methods for combining these modal impedances into a total radiation impedance for the transducer will be presented. The effect of relative orientation of the transducers on the radiation impedance is investigated. The results will be compared to equivalent circuit models and experimental data. [This work was sponsored by the Office of Naval Research.]