Bubble size distribution estimation via void rate dissipation in gas saturated liquid. Application to ultrasonic cavitation bubble fields

A hyper-frequency method enabling to investigate into the bubble size distribution of a bubble cloud in which bubble radii are lower than the equilibrium one is displayed. It is based on analysing the void rate dissipation after the acoustic irradiation is switched off in terms of bubble dissolution. The experimental evaluation of this method has been performed in air saturated water with cavitation bubble cloud generated in a 308 kHz stationary acoustic field. The size distributions achieve range from 19 μm to 59 μm and allow to follow the influences of both the acoustic pressure and the irradiation duration on them. By taking into account the bubble coalescences occurring during the bubble rise after the end of the acoustic irradiation, the raw distributions have been qualitatively nuanced thanks to the exploitation of a probabilistic model of free bubble coalescence.