Abstract:
Recently, there has been substantial progress in predicting the penetration of sonic boom noise into the ocean. Such noise penetration occurs for either commercial or military supersonic aircraft operating over the ocean. As previously discussed [J. Acoust. Soc. Am. 97, 3258(A) (1995)], one can use analytical techniques to make predictions of the noise penetration, but eventually finite difference calculations become the method of choice when accounting for wind wave swell and ocean inhomogeneities. Two-dimensional calculations already indicate that typical wind wave swell can focus or defocus a penetrating rounded sonic boom waveform up to approximately (plus or minus)1.5 dB for a homogeneous ocean below a homogeneous atmosphere. Higher Mach number supersonic flight accentuates the focusing. Predictions are currently being sought for more realistic sonic boom waveform shapes, three-dimensional interactions between the incident boom and the ocean swell, and the effects of bubble plumes immediately below the ocean surface. One simulation of the focusing from ocean swell will be visualized via a videotape. [Work supported by NASA Langley Research Center, under Grant NAG 1--1638, and by Armstrong Laboratory, Air Force Material Command, USAF, under Grant F41624--96--1-0003.]