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Published 1995 | public
Journal Article Open

Observations and Scalling of Travelling Bubble Cavitation

Abstract

Recent observations of growing and collapsing bubbles in flows over axisymmetric headforms have revealed the complexity of the 'micro-fluid-mechanics' associated with these bubbles (van der Meulen & van Renesse 1989; Briancon-Marjollet et al. 1990; Ceccio & Brennen 1991). Among the complex features observed were the bubble-to-bubble and bubble-to-boundary-layer interactions which leads to the shearing of the underside of the bubble and alters the collapsing process. All of these previous tests, though, were performed on small headform sizes. The focus of this research is to analyse the scaling effects of these phenomena due to variations in model size, Reynolds number and cavitation number. For this purpose, cavitating flows over Schiebe headforms of different sizes (5.08, 25.4 and 50.8 cm in diameter) were studied in the David Taylor Large Cavitation Channel (LCC). The bubble dynamics captured using high-speed film and electrode sensors are presented along with the noise signals generated during the collapse of the cavities. In the light of the complexity of the dynamics of the travelling bubbles and the important bubble/bubble interactions, it is clear that the spherical Rayleigh-Plesset analysis cannot reproduce many of the phenomena observed. For this purpose an unsteady numerical code was developed which uses travelling sources to model the interactions between the bubble (or bubbles) and the pressure gradients in the irrotational flow outside the boundary layer on the headform. The paper compares the results of this numerical code with the present experimental results and demonstrates good qualitative agreement between the two.

Additional Information

(Received 3 February 1994 and in revised form 13 October 1994) Large-scale experiments like these require help of many people and the authors are very grateful to all of those who helped in this enterprise. We are very grateful to the ONR for their support under contracts N00014-91-5-1426 (S. L. C.) and N00014-91-J-1295 (C.E.B., Y.K.deC.). We are also extremely grateful to the David Taylor Research Center (DTRC) and to their staff including W. B. Morgan for making the use of the LCC possible for us. From DTRC. Young Shen, Scott Gowing and James Blanton were important and valued members of the team who conducted the experiments. Po-Wen Yu (University of Michigan) was responsible for all the photographic aspects of the experiments, and Douglas Hart (Caltech) provided much assistance during the tests. The staff at the LCC in Memphis, Tennessee were remarkably tolerant and helpful and we wish to thank all of them most sincerely; we are particularly grateful to Bob Etter whose constant support was invaluable. "Reprinted with the permission of Cambridge University Press."

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August 22, 2023
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October 13, 2023