Experimental Study on Bubble Nucleation in the Oscillating Pressure Field

In bubble nucleation under the oscillating pressure field, when the oscillation period τ is of the same order of magnitude as the characteristic time τn of bubble nucleation, it is expected that the distribution of radius of bubble embryo in liquid will be largely affected by the pressure oscillation and the degree of superheat limit may change. In order to clarify this point, superheat limits of homogeneous nucleation under the oscillating pressure field generated by ultrasonic oscillators are measured for propane with and without dissolved carbon dioxide by the floating droplet method. From the experimental results it is found that when τ > τn the measured superheat limit agrees with that calculated by the conventional theory where the quasi-steady state is assumed, but the bubble nucleation occurs at temperature lower than that preducted by the theory when τ nearly equals τn. It is also found that the characteristic time of bubble nucleation is changed by the amount of dissolved carbon dioxide.