Sound Transmission from a Tapered Fluid Layer into a Fast Bottom.
NAVAL POSTGRADUATE SCHOOL MONTEREY CALIF
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Acoustic energy transfer from a tapered fluid layer into a fast bottom was investigated experimentally using fresh water and a saline solution separated by a sheet of 0.5 mil mylar. A 150 kHz pulsed signal was excited in the upper layer and a receiver in the lower fluid layer was used to determine the acoustic field. Measurements were made for taper angles of 1.52, 2.51, and 4.41 deg and for rhoc ratios of 0.745 and 0.836. Beams were observed in the lower layer, beginning at points where the depth of the tapered layer equals a cutoff depth for a normal mode. The experimental beam patterns agree well with the theoretical predictions for angles from grazing to the angle where the maximum pressure amplitude is reached. For greater angles, experiment and theory significantly diverge. Author