Experiment on acoustic wave propagation in a bubbly water: Frequency influence

Abstract

Commander and Prosperetti works [J. Acoust. Soc. Am. 85, 732–746 (1989)] show that an acoustic wave, propagating in a bubbly water, is very strongly damped and its phase speed is disturbed for bubble resonance frequency neighboring. In relation to our experimental results, numerical results obtained with these analytical works are presented. Experiments are realized in a large water-filled tank. A frequency modulated burst, generated with broadband transducers of central frequency 100, 200, and 500 kHz, propagates through the bubble cloud obtained by a high pressure water jet. Our measurements show simultaneously, after the stop of jet, a strong damping of acoustic signal and a small change of its phase speed. After some minutes, this signal gets back progressively its initial amplitude and phase speed values. One can notice that the acoustic signal amplitude and phase speed are not identical in all emission frequency domain. To explain this phenomenon, we assume the existence of frequency band gaps related to the multiple scattering from the bubble cloud. [Work supported by Bassin d’Essais des Carènes (France).]