ASA 124th Meeting New Orleans 1992 October

3pSA1. Forward and backward projection of axisymmetric pressure fields from shells of revolution using an internal source density method.

Peter R. Stepanishen

Dept. of Ocean Eng., Univ. of Rhode Island, Kingston, RI 02881

Janet Hillenbr

Naval Undersea Warfare Ctr., Newport, RI 02841

The forward and backward projection of measured harmonic pressure fields from complex vibrators is a subject of considerable interest in the areas of transducer calibration and structural acoustics. A general methodology for addressing such projection problems for surfaces of revolution using internal line source density distributions along the axis of the body is presented. The focus of the present paper is however on the rotationally symmetric problem. A least-mean-square error method is used to determine an internal line monopole source density distribution along the axis of symmetry of the measurement surface by matching the measured pressure in the field to the pressure field of the source distribution at the surface. The resultant source density distribution can then be used to determine the pressure and velocity fields exterior to the body of revolution; hence, the measured pressure field can be forward and backward projected. Numerical results are presented to illustrate the accuracy of the projection method for the case of spherical, spheroidal, and finite cylindrical vibrators with rotationally symmetric velocities.