ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

2pEA6. Variation model for the radiation impedance of Class IV transducers III.

Harold C. Robinson

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

Previously [H. C. Robinson and E. A. McLaughlin, J. Acoust. Soc. Am. 97, 3300(A) (1995)], the modal radiation impedance for a pair of Class IV transducers was calculated using variational methods. This model determines distinct self and mutual radiation impedance contributions between pairs of surface velocity modes, including the effects of element orientation, without requiring exact solutions to the equations of motion and boundary conditions. However, in order to model the total radiation impedance of the transducers, suitable methods for combining these modal impedances must be determined, which in turn requires that some estimate of the relative importance of each modal contribution be made. One method of determining the relative strengths is singular value decomposition [G. W. Benthien, Naval Ocean Systems Center Technical Report 1329, November 1989], which effectively allows one to determine the fluid-loaded resonances of the transducer and their associated eigenvectors. The relative magnitudes of these in-water modes will determine their importance in the total impedance. The results of this combination will be incorporated in a modified equivalent circuit which includes the effects of the ``banana'' mode. Calculations using this circuit will be made to existing equivalent circuit models as well as to experimental data.