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

2pEA9. Acoustic pressure field evaluation of an annular cylindrical array for underwater pipeline inspection.

R. Sumangala

P. R. Saseendran Pillai

Dept. of Electron., Cochin Univ. of Sci. and Technol., Cochin-682 022, India

Evaluation of the effective acoustic pressure field of a continuous wave, optimum spaced, point source, annular cylindrical array for underwater pipeline inspection is featured in this paper. A section of the array comprised of mxn elements is selectively energized to illuminate the region to be tested and a similarly grouped set of remaining array elements function as receivers. A steady half-power beamwidth and sidelobe levels were obtained for a radius of the array greater than 40(lambda). The portion of the energy reflected or reradiated from the contours of the pipeline and captured by the point source elements being nominally small can be neglected for all practical purposes. Effective acoustic pressure is computed as the Fourier transform of the impulse response of the array elements h[inf mn](r,t) determined using the Green's function approach. The total effective acoustic pressure over the contour of the pipeline is the sum of the weighted contributions from all radiating set of elements. A good focusing effect can be achieved by optimizing the number of elements and the radius of the array. [Work supported by CSIR INDIA.]