### 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
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*Dept. of Ocean Eng., Univ. of Rhode Island, Kingston, RI 02881
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**Janet Hillenbr
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*Naval Undersea Warfare Ctr., Newport, RI 02841
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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.