Research on the Relationship Between Sound Velocity and Void Fraction in Bubbly Flow

Bubbly flows are widely found in nature, engineering equipment, and many areas of daily life. With the increasing level of science and technology, the measurement of void fraction in bubble flow is now urgently needed to be solved. In this paper, WOOD, Lee and Commander's theoretical models of sound velocity are studied. By comparing the predicted sound velocity of these models to experiment data, it is found that all three theoretical models in the low-frequency range are consistent with experimental data. Only the Commander's theoretical model can match the experimental data in the non-low-frequency range. It shows that Commander's theoretical model is suitable for all frequency bands, while WOOD and Lee models are only suitable for low frequency band. Therefore, low-frequency and non-low-frequency ranges are divided using Commander's theory in conjunction with the ratio of emitted wave frequency to bubble resonance frequency. 0.92 is selected as the boundary ratio between the low-frequency and non-low-frequency ranges. At low void fraction, it is shown that the sound velocity decreases largely with increasing void fraction at low-frequency range and increases with increasing void fraction at non-low-frequency range. Furthermore, the pressure acoustic simulation is also applied to verify these results.