Characterization of cavitation in a flow-through exposure chamber by means of a resonant bubble detector |
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Authors: | DL Miller AR Williams DR Gross |
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Institution: | 1. Department of Physics, University of Vermont, Burlington, Vermont 05405, USA;2. Department of Medical Biophysics, University of Manchester, Manchester, M13 3PT, UK;3. Department of Veterinary Physiology and Pharmacology, Texas A & M University, College Station, Texas 77843, USA |
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Abstract: | Ultrasonic cavitation at frequencies of 0.514, 0.866, 1.03 and 1.61 MHz in water flowing through tubes was observed by counting bubbles downstream with a resonant bubble detector (RBD) operated at 0.89 or 1.7 MHz. In a 21 mm diameter, thin-walled tube, cavitation thresholds in tap water flowing at 5.3 cm s?1 ranged from 2.0 – 2.5 bar at 0.514 MHz to 3 – 4 bar at 1.61 MHz. When high speed injections were employed to trigger the ultrasonic cavitation with hydrodynamically-generated bubbles, the thresholds were reduced to about 2 bar and bubble production was enhanced for 1.03 and 1.61 MHz exposures. Ultrasonic radiation forces on the bubbles and bubble coalescence appeared to cause, under some conditions, a reduction in bubble counts during subthreshold exposures when bubbles were injected into the flow. The RBD method is a useful tool for detecting and semi-quantitatively observing cavitation in a flow-through exposure system. |
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Keywords: | ultrasonics cavitation bubble dynamics |
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