A sensor for measuring low frequency surface vibration of a fluid loaded compliant structure
- NUWC Division, Newport, Underwater Sound Reference Detachment, P.O. Box 568337, Orlando, Florida 32856-8337 (United States)
- D. H. Trivett, Inc., P.O. Box 560771, Orlando, Florida 32856-0771 (United States)
The most common method of directly measuring the vibration of a fluid-loaded structure is through the use of accelerometers mounted on the surface. When that surface consists of a low density, highly-compliant material it is necessary to take steps to insure that the sensor does not influence the motion of the surface. This can be accomplished with the use of small, neutrally-buoyant accelerometers. However, if low frequency measurements are desired, where the acceleration is small, the signal-to-noise ratio obtained with small, low sensitivity accelerometers may not be acceptable. To address the problem of low-frequency measurements of a submerged compliant surface the Underwater Sound Reference Department of the Naval Undersea Warfare Center (NUWC/USRD) has developed a class of neutrally-buoyant capacitive displacement sensors. A displacement sensor requires that the mass-spring system, which constitutes the detector, be operated above the resonance frequency, resulting in the mass being inertial. Thus, only the dynamic mass of these sensors needs to be equal to the mass of the displaced fluid so as to not alter the mass of the surface to be measured. These sensors are intended for use in the Anechoic Tank Facility at NUWC/USRD and must be capable of operating at hydrostatic pressures of 4.1 MPa (600 psi) and over a temperature range of {minus}4 to 40{degree}C, while being rigid enough so that they neither affect nor are sensitive to the incident acoustic field. Since the sensor responds to the displacement of the surface, instead of the acceleration, these sensors are ideally suited for low frequency measurements. Both their design as well as experimental results will be presented. {copyright} {ital 1996 American Institute of Physics.}
- OSTI ID:
- 288379
- Report Number(s):
- CONF-9509298-; ISSN 0094-243X; TRN: 9615M0122
- Journal Information:
- AIP Conference Proceedings, Vol. 368, Issue 1; Conference: Acoustic velocity sensor focused workshop, Mystic, CT (United States), 12-13 Sep 1995; Other Information: PBD: Apr 1996
- Country of Publication:
- United States
- Language:
- English
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