Mechanisms of bubble effects on acoustic propagation characteristics in high-temperature and high-pressure bubble flows

In the complex gas-liquid two-phase flow environment of the nucleate boiling region outside the heat-exchange pipes of steam generators, acoustic propagation is influenced by multiple factors. Previous research has largely considered how the bubble distribution and acoustic frequency affect the acoustic velocity and attenuation, whereas the role of boundary-layer thickness in acoustic propagation has not been explored systematically. Using bubble damping theory and the linear model of acoustic propagation in water containing monodisperse bubbles, derived here is the relationship among acoustic velocity, acoustic attenuation, and boundary-layer thickness in bubble flow. Also established is a numerical model for acoustic propagation in bubble flow under high temperature and pressure, and how the bubble distribution and acoustic frequency affect the sound field is analyzed. This study reveals the factors influencing bubble damping and how it regulates acoustic attenuation, providing insight into how acoustic waves propagate in gas-liquid two-phase flows.