Measurements of the peak pressure and sound exposure level from underwater explosions

Abstract

There is an interest by the Navy to determine the sound field produced by underwater explosions to minimize the impact on marine life during training exercises. This work presents measurements of underwater explosions collected 7 km off the coast of Virginia in shallow water (depth 14 m) with sound speed conditions considered approximately iso-speed. Explosive charges with TNT equivalent weight 0.1 to 6.0 kg (W) were deployed at approximately mid-water and bottom depths. Acoustic data were recorded using a 9 element vertical line array at range 430 m and single-element autonomous systems at ranges 170, 430, and 950 m. The peak pressures and sound exposure levels (SEL) are calculated from the data; at 430 m peak pressures as high as 220 dB re 1 μPa and SEL as high as 190 dB re 1 μPa2 s were measured. The peak pressures are compared to semi-empirical equations that are functions of range and W to the one-third power, such as Arons [J. Acoust. Soc. Am. 26, 343-346 (1954)], and both the peak pressures and SEL are compared to simulations obtained using the parabolic wave equation. [Research supported by Naval Facilities Engineering Command.]