Evaluation of a standing wave system for determining the presence and acoustic effect of microbubbles near the sea surface.
That bubbles affect sound propagation in the ocean has long been known. However,, quantitative data on the concentrations and distribution of bubbles near the surface of the ocean is not available. A one-dimensional, high Q, standing wave system was constructed and evaluated to determine bubble...
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| Language: | en_US |
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Monterey, California ; Naval Postgraduate School
2012
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| Online Access: | http://hdl.handle.net/10945/12130 |
| Summary: | That bubbles affect sound propagation in the ocean
has long been known. However,, quantitative data on the
concentrations and distribution of bubbles near the surface
of the ocean is not available. A one-dimensional,
high Q, standing wave system was constructed and evaluated
to determine bubble concentrations by measuring the effect
of bubbles on the system Q's. It was tested to depths of
40 feet and in the frequency range of 10-100 kHz. This
system used a mylar electrostatic transducer as the
sound source and also as one of the reflectors. System
Q's of 3500 were obtained. It was possible to measure
attenuation to t 0,019 db/m above 20 kHz. Hydrostatic pressure caused variations in the face of the transducer
thereby making the system unstable. The mylar transducer
is therefore unsuitable for use as both source and
reflector. Initial investigations made into using the mylar
transducer to externally excite a reflector-reflector
system are also described. |
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