Acoustics of Travelling Bubble Cavitation
Experiments on cavitation prove that the noise level is highly dependent on the type of cavitation. Usually it is expected that bubble cavitation is much less severe than cloud cavitation. To verify this expectation, noise measurements on a bubble stream over a hydrofoil were done at Marin (Wageningen ,The Netherlands). These experiments show that there is not much difference irrespective of the fact whether the bubbly flow is clustering or not.
In this paper the noise level produced by a macroscopically steady bubbly layer on a hydrofoil is predicted analytically, based on the stochastic properties of the fluctuating quantities in the layer. This analysis uses the technique of Fourier-Stieltjes transformation as used by O.M. Phillips. In this way, the sound spectrum outside the bubble layer can be correlated to the covariance of the fluctuating quantities, as gasfraction, velocity etc.,assuming for instance that the bubble layer is stochastically stationairy and almost homogeneous.
Based on this theory an estimate can be made of the relative importance of cluster formation, in dealing with the sound production of bubble layers.
KeywordsVortex Covariance Cavitation Acoustics Marin
Unable to display preview. Download preview PDF.
- 1.Knapp, R.T.; Daily J.W.; Hammitt F.G.: Cavitation. McGraw-Hill Book Company 1970Google Scholar
- 3.van der Kooij, J.: Geluidsproduktie door luchtbellen in water bij passage langs een vleugelprofiel. MARIN Rapport No. 45978–1-VT (1985) In Dutch.Google Scholar
- 6.Buist, J.; Sound production of a stochastically stationary bubbly layer. Forthcoming PH. D. thesis.Google Scholar
- 7.Phillips, O.M.: The dynamics of the upper ocean, Cambrigde University Press 1966Google Scholar
- 8.Wijngaarden, L.; Omta, R.; Hydrodynamics of cavitation noise, THD Schriftenreihe Wissenschaft und Technic 28 (1986) 219–226Google Scholar