Abstract:

In order to reveal the characteristics of resonant frequency of the cavitation bubbles in supercritical fluid CO2 radiated with ultrasonic, the laws of the resonant frequency varying with the original radius of the bubbles, the fluid pressure and the fluid temperature were investigated based on the Rayleigh-Plesset equation. The results indicate that the resonant frequency of cavitation bubbles in supercritical fluid CO2 decreases with the increase in the original radius, increases with the fluid temperature, and decreases with the increase in fluid pressure till to a minimum value at 18 MPa. It is also found that, at the same initial bubble radius, the cavitation bubbles in supercritical fluid CO2 is of higher resonant frequency than that in water, and that the acoustic pressure for the cavitation bubble collapse in a ultrasonic period reaches the lowest value when the ultrasonic frequency is close to the natural resonant frequency of cavitation bubbles.

Key words: supercritical fluid CO₂, ultrasonic, cavitation, resonant frequency, pressure, temperature