Characterization of a large volume spherical resonator for studies of acoustically induced cavitation in liquids

Abstract

This paper describes a spherical acoustical resonator system used to study acoustic cavitation phenomena in liquids as part of an effort to scale up the energy density of collapse of transient cavitation. The resonator is formed by a stainless steel spherical shell 24.1 cm in diameter (OD) and either 1.27 cm or 1.90 cm thick designed for generating transient cavitation at high static pressures. An external transducer attached to the surface of the resonator was used to excite an acoustic standing wave in the liquid in order to generate a pressure maximum near the center of the liquid. We will present the results of our characterization of this device, including hydrophone measurements of the acoustic pressure generated in the liquid and vibration analysis on the surface of the resonator carried out using laser Doppler vibrometry. The resonance frequency spectrum and modal structure are compared to numerical predictions using theory developed by (Mehl, JASA 78(2), 782–788 (1985)) [Work supported by SMDC Contract No. W9113M-07-C-0178.]

The effect of static pressure on the inertial cavitation threshold

“…(1) at driving amplitudes much lower than those used to initiate cavitation. 16 Furthermore, the maximum pressure anti-node at r ¼ 0 was found to be linear with the driving amplitude near the cavitation threshold, as described in Ref. 17.…”

“…Since the quality factor of the system was so large, it was critical that the system be continuously driven at resonance. 16 This was accomplished by the use of a custom-designed phase locked loop (PLL) manufactured by IDI.…”

Suppression of an acoustic mode by an elastic mode of a liquid-filled spherical shell resonator

“…A spherical acoustical resonator system used to study acoustic cavitation phenomena in liquids has been previously reported. 1 An external transducer attached to the surface of the resonator was used to excite an acoustic standing wave in the liquid. A similar resonator system exhibited transient acoustic cavitation in water at static pressures up to 300 bars.…”

“…On the other hand, the circles "*" and the boxs "h" are calculated using the empty shell and the rigid boundary limits, respectively. The(2,4),(6,1), and (7,1) modes are classified as elastic while the rest of the modes shown here are classified as acoustic.…”