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Scale Effects on Cavitation Inception in Submerged Jets

Ooi, Kean Khoon (1981) Scale Effects on Cavitation Inception in Submerged Jets. California Institute of Technology , Pasadena, CA. http://resolver.caltech.edu/CaltechAUTHORS:20140110-162013289

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Abstract

The present work is an investigation into the scale effects on cavitation inception in submerged water jets. Four scale effects were studied: (i) jet size, (ii) jet velocity, (iii) dissolved air content, and (iv) the nuclei population in the flow. The nuclei population was artificially altered by "electrolysis seeding." Holography and schlieren photography were used to observe the flow. Direct measurements of the nuclei population were also accomplished by holography. In addition, the instantaneous pressure field in the jet was successfully mapped out using specially tailored bubbles as pressure sensors. It was found that inception did not generally occur in the cores of the turbulent eddies and that the region in which the cavities were first seen were dependent on the size of the jet. Pressure measurements showed that negative peak pressure fluctuation intensities of as high as 120 percent of the dynamic head existed in the jet. The results also revealed that the instantaneous pressure fluctuations have a slightly skewed bell shape probability distribution. For the present tests, the inception index was independent of the exit velocity for a constant size jet. However, when the flow was seeded, the inception number showed a linear dependence on velocity and this dependence increased with increased number of seeded nuclei. The effects of the nuclei number density and pressure fluctuations are incorporated in a "probable cavitation occurrence" parameter which shows promise in reducing scatter in this type of experiment.


Item Type:Report or Paper (Technical Report)
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http://resolver.caltech.edu/CaltechETD:etd-09202006-102904Related ItemUNSPECIFIED
Additional Information:This work was supported by Naval Sea Systems Command General Hydromechanics Research Program administered by the David Taylor Naval Research and Development Center under Contract No. N00014-75-C-038. Approved for public release; distribution unlimited. Report No. Eng. 183-6 December 1981. Approved by: A.J. Acosta. I would like to express my gratitude and thanks to my thesis advisor, Professor A.J. Acosta, for his invaluaole assistance, guidance and advice throughout the course of the present work. His concern for the welfare of this writer is. deeply appreciated. Thanks also go to Professor R.H. Sabersky who expressed a continuing interest in this research work and for his many helpful suggestions and comments. Dr. D. Oldenziel provided useful suggestions and stimulating discussions. This is gratefully acknowledged. I would like to thank my colleague J. Katz. His advice and assistance on matters related to holography were instrumental in bringing about a successful completion of the present holographic studies. E.F. Daly is deserving of special mention for his help during the design ~tages of the experimental apparatus. He has never ceased to amaze this writer with his uncanny design abilities. I am also grateful to J. Fontana who did the machining and assembly of the various components of the experimental equipment. Thanks are due too, to R. Eastvedt and L. Montenegro for their assistance. Several students helped in the processing of films and data reduction. In this respect, I would like to thank Catherine Petrov, Ronald Franz and Tawach Ungsuwarungsri. I am grateful to Susan Berkley and Rennie Dudek for their help and friendship. They have gone out of their way to accommodate the wishes of this writer, for which I am thankful. I would like to acknowledge the financial support of the Institute and of the Naval Sea System Command General Hydrodynamic Research Program administered by David W. Taylor Naval Ship Research and Development Center. Finally, I would like to express my deepest thanks to my family for their never ending support. It is to them and the memories of my mother that I dedicate this work.
Funders:
Funding AgencyGrant Number
David Taylor Naval Research and Development CenterN00014-75-C-038
Subject Keywords:cavitation, cavitation inception, cavitating jets, cavitation nuclei, jets -- pressure fluctuations in, jets -- flow visualization of.
Record Number:CaltechAUTHORS:20140110-162013289
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20140110-162013289
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:43323
Collection:CaltechAUTHORS
Deposited By: Kristin Buxton
Deposited On:11 Jan 2014 00:44
Last Modified:11 Jan 2014 00:44

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