Characteristic analysis of cavitation bubbles in carbon dioxide fluid

Abstract After analysing the characteristics of bubble cavitation in high-pressure carbon dioxide (CO2) fluid, cavitation conditions and some correlative physical characteristics are investigated. The results show that the ultrasonic intensity of liquid carbon dioxide to make cavitation occur is affected by the initial radius of the bubbles, hydrostatic pressure, temperature and vapour pressure within the bubbles in liquid CO2. At the low frequency of ultrasound, the phase-speed of the liquid CO2 gradually approaches the sound speed of the pure liquid when void fraction increases. At high frequency, the phase-speed is nearly equal to the sound speed in the liquid under different void fractions. The attenuation of ultrasound in liquid carbon dioxide reaches a maximum near the resonance frequency and then decreases when frequency either increases or decreases. At the resonance frequency, the phase-speed and the attenuation increase when the void fraction increases. Keywords: carbon dioxideultrasonic cavitationcavitation bubbleinitial radiusphase speedattenuation Acknowledgements This work is supported by National Natural Science Foundation of China, Grant No. 10674048 and by Guangdong Provincial Natural Science Foundation, Grant No. 06025714.