The Distribution of Acoustic Field Intensity in a Medium with Sound Velocity Gradient Using a Modified Sound Ray Density Method

摘要

The previous paper, presented a sound ray density method which assumed that a ray representing an acoustic wave carries a specific acoustic power and that the -acoustic wave's intensity is in proportion to the number of rays passing through an elementary area. Subsequent measurements of wave intensity range distribution in inland waters confirmed the method at the same time revealing some of its deficiencies. The algorithm could be used to determine field intensity distribution for a conic transmitting antenna beam only. Also the first phase did not include the problem of acoustic wave absorption. This article presents a modified sound ray density method to allow the inclusion of model and actual hydroacoustic antenna beam patterns. It also discusses absorption and how it could be taken into account in computing field intensity distribution. Acoustic field intensity distribution in a medium with a known sound velocity gradient was studied taking into account the actual shape of the transmitting antenna's beam patterns. The results indicate the need for a renewed consideration of several aspects of designing and evaluating the detection capability of hydroacoustic systems. The major aspects include the level of side lobes, accuracy of target bearing and distance and a modification of the form of range equation to one that will include the phenomenon of refraction.