Small Explosive Sources for Use in Underwater Sound Experiments on Ships

摘要

The use of 40 gram charges as underwater sound sources in reciprocal measurements of sound transmission in ships was investigated. A series of ten TNT charges was detonated in shallow water (approximate depth: 5 m). Sound propagation to hydrophones at a distance of 48 m and 165 m was compared with that for a CW source. Results show that nonlinearities or bubble migration have no influence on the sound attenuation between these hydrophones. A large number of sound transmission measurements were performed on board a frigate, using as a source underwater explosions of 40 g plastic charges at a distance of approximately 25 m. Again comparison with a CW source does not reveal any nonlinear influences. To obtain the full advantage of the large source strengths, it is recommended that the dynamic range of the response signals be reduced before recording, for instance by application of low pass filters. Otherwise many low frequency measurements are lost due to the dynamic range limitations of the tape recorders.