Estimation of bubble density with subharmonic acoustic wave in bubbly water

Abstract

Bubble density was estimated with a subharmonic acoustic wave generatedin bubbly water. The subharmonic acoustic wave can be easilygenerated due to the nonlinearity of bubbly water if the frequency ofprimary acoustic wave is double of the bubble resonance frequency andthe driving acoustic pressure amplitude exceeds a certain threshold value.The frequency of primary acoustic wave was varied from 200 kHz to 500kHz while the bubble resonance radius at subharmonic frequency wasfrom 12 um to 28 um. The pressure level of the subharmonic acousticwave linearly increased as the driving acoustic pressure amplitude increased.With the subharmonic pressure level, the bubble density was estimatedfrom nonlinear bubble oscillation equation Yu. A. Ilinskii and E. A. Zabolotskaya, J. Acoust. Soc. Am. 92, 2837–2841 1992 . The estimatedbubble densities were also compared with those from a linear conventionalacoustic bubble sizing method. Bubble sizing with subharmonicacoustic wave seems to be easily utilized for the diagnosis of sandy sedimentwith bubbles.