Acoustic bubble counting technique using sound speed extracted from sound attenuation

Abstract

Sound attenuation has been solely used to estimate bubble size distributions of bubbly water in the conventional acoustic bubble sizing methods. These conventional methods are useful for the void fraction around 10(-6) or lower. However, the change of compressibility in the bubbly water also should be considered in bubble sizing for the void fraction around 10(-5) or higher. Recently, the sound speed as well as sound attenuation was considered for acoustic bubble size estimation in bubbly water. In this paper, the sound speed estimated from sound attenuation in bubbly water by an iterative method is used for a bubble counting. This new iterative inverse bubble sizing technique is numerically tested for bubble distributions of single-size, Gaussian, and power-law functions. The numerical simulation results are in agreement with the given bubble distributions even for the high void fractions of 10(-4)-10(-3). It suggests that the iterative inverse technique can be a very powerful tool for practical use in acoustic bubble counting in the ocean.