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Published December 1, 1991 | public
Journal Article Open

Separation and Surface Nuclei Effects in a Cavitation Susceptibility Meter

Abstract

This work is concerned with the effects of flow separation and surface nuclei on the operation of a fixed geometry Cavitation Susceptibility Meter (CSM) with laminar flow. Cavitation is induced under controlled conditions at the throat of a glass venturi tube for the measurement of the active nuclei concentration in water samples as a function of the applied tension. Both cavitation and flow velocity are monitored optically by a Laser Doppler Velocimeter. The throat pressure is determined indirectly from the upstream pressure and the local flow velocity. The results show that laminar flow separation and surface nuclei effects are the most stringent operational limitations. Separation in the diffuser increases the minimum attainable throat pressure above the susceptibility of most cavitation nuclei commonly found in technical waters. Surface nuclei can generate extensive sheet or spot cavitation at relatively high tensions even on optically finished glass surfaces. These phenomena are difficult to eliminate and bring therefore into question the practical utility of CSM's with laminar flow and fixed geometry for the measurement of the dependence of the cavitating nuclei concentration over wide ranges of the applied tension, as required for cavitation studies.

Additional Information

Contributed by the Fluids Engineering Division for publication in the Journal of Fluids Engineeering. Manuscript received by the Fluids Engineering Division May 31, 1990. This research has been funded by the Office of Naval Research and by the Naval Sea Systems Command General Hydromechanics Research Program administered by the David W. Taylor Naval Ship Research and Development Center. The North Atlantic Treaty Organization - Consiglio Nazionale delle Ricerche, Italy, has also contributed to the support of this work through a 1982 and a 1983 Fellowship for Technological Research. Special thanks to Dr. T. T. Huang of DTNSRDC for his interest in this work, to Mr. Joe Fontana, Mr. Elton Daly, Mr. Rich Eastvedt, Mr. Leonard Montenegro, Mr. John Lee and to Miss Cecilia Lin of the Caltech staff for their assistance in the completion of the experiment and to Dr. Haskel Shapiro, Mr. Bob Kirkpatrick and their group for the design and implementation of the custum-made electronics.

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August 22, 2023
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October 13, 2023