Accession Number : AD0656913

Title :   TWO FORTRAN PROGRAMS (0577 AND 0717) FOR COMPUTING ELECTROACOUSTICAL BEHAVIOR OF TRANSMITTING SONAR ARRAYS,

Corporate Author : NAVY UNDERWATER SOUND LAB NEW LONDON CONN

Personal Author(s) : Porter,David T.

Report Date : 15 JUN 1967

Pagination or Media Count : 49

Abstract : The Underwater Sound Laboratory's FORTRAN Programs 0577 and 0717 compute the steady-state electrical, mechanical, and acoustical behavior of transmitting sonar arrays. These programs, which have considerable flexibility, are able to accommodate up to three different arrays on the same baffle; and, since the transducers in these arrays need not be identical, 'stagger-tuned' arrays can be used. The arrays may be mounted on rigid planar, cylindrical, or spherical baffles. Based on the transducer characteristics that are read in as input data, Programs 0577 and 0717 compute an equivalent circuit and from it a Thevenin-equivalent circuit. Pritchard's mutual impedance formula is used to compute a mutual impedance matrix. The transducer driving forces are generated from the given amplifier data; knowledge of the equivalent circuit; and the phasing, steering, and shading to be used. Depending on the size of the array, the transducer face velocities are computed from the equations relating them to the driving forces and mutual impedance matrix either by direct matrix inversion (Program 0577) or an iterative patch method (Program 0717). Then the radiation impedances, electrical input impedances, and electrical powers, currents, voltages, efficiency, etc., can be computed. The farfield pressure pattern and source level are determined by the face velocities and appropriate element directivity patterns. The directivity index is obtained from knowledge of the source level, total electric power, and efficiency. A plan is given for a more detailed analysis of a transmitting array, including its sonar dome. The analysis would be done by six computer programs run sequentially. (Author)

Descriptors :   (*SONAR ARRAYS, *COMPUTER PROGRAMS), BAFFLES, PERFORMANCE(ENGINEERING), MATHEMATICAL MODELS, ACOUSTIC IMPEDANCE

Subject Categories : Acoustic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE