Title: The radiation from free-free beams in air and in water
Abstract: The acoustic radiation from a series of free-free, point driven beams has been studied bothanalytically and experimentally. The radiated power due to a prescribed transverse beam motion was analytically predicted by modeling the beam as a finite, long, slender strip with a thin elliptical cross section. The neutral axis of the beam was coincident with the major axis of the cross-section. Two extremes of baffled (no fluid motion across the plane coincident with the beam major axis) and unbaffled (fluid motion permitted across that plane) beams are discussed analytically. Experimental verification in the form of measurements of radiated power relative to mean-square beam velocity is provided. Baffled and unbaffled beams radiate the same power per mean square velocity when the ratio of the acoustic wave length to the beam width is less than π/2. At lower frequencies radiation from the unbaffled beam depends on an additional frequency-squared factor. Measurements of vibration mode shapes and acoustic radiation, were made in both air andwater, beams of identical geometry but different densities being used. No effects of heavy fluid loading could be detected. The combined acoustic data for a given beam in both air and water covered a wave number range from well below to well above acoustic coincidence. In general, the measured radiation efficiencies and entrained inertia were closely predicted by the theory.
Publication Year: 1974
Publication Date: 1974-04-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 39
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