Reisman, G. E. and Wang, Y.-C. and Brennen, C. E. (1998) Observations of Shock Waves in Cloud Cavitation. Journal of Fluid Mechanics, 355 . pp. 255-283. ISSN 0022-1120. http://resolver.caltech.edu/CaltechAUTHORS:REIjfm98
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This paper describes an investigation of the dynamics and acoustics of cloud cavitation, the structures which are often formed by the periodic breakup and collapse of a sheet or vortex cavity. This form of cavitation frequently causes severe noise and damage, though the precise mechanism responsible for the enhancement of these adverse effects is not fully understood. In this paper, we investigate the large impulsive surface pressures generated by this type of cavitation and correlate these with the images from high-speed motion pictures. This reveals that several types of propagating structures (shock waves) are formed in a collapsing cloud and dictate the dynamics and acoustics of collapse. One type of shock wave structure is associated with the coherent collapse of a well-defined and separate cloud when it is convected into a region of higher pressure. This type of global structure causes the largest impulsive pressures and radiated noise. But two other types of structure, termed 'crescent-shaped regions' and 'leading-edge structures' occur during the less-coherent collapse of clouds. These local events are smaller and therefore produce less radiated noise but the interior pressure pulse magnitudes are almost as large as those produced by the global events. The ubiquity and severity of these propagating shock wave structures provides a new perspective on the mechanisms reponsible for noise and damage in cavitating flows involving clouds of bubbles. It would appear that shock wave dynamics rather than the collapse dynamics of single bubbles determine the damage and noise in many cavitating flows.
|Additional Information:||This research program was supported by the Office of Naval Research under grant number N00014-91-J-1295. The authors also greatly appreciate the advice and encouragement of Professor Allan Acosta and the help of Douglas Hart, Beth McKenney, Fabrizio d'Auria, Roberto Zenit, Tricia Waniewski, Don Kwak, Amy Herr and Amir Alagheband. "Reprinted with the permission of Cambridge University Press."|
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|Deposited By:||Christopher Brennen|
|Deposited On:||29 Oct 2004|
|Last Modified:||26 Dec 2012 08:39|
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