Characterization of Bubble Size of Gas–Liquid Two-Phase Flow Using Ultrasonic Signals

Refining the bubble size distribution characteristics in gas–liquid two-phase flow can enhance the precision of detecting flow parameters. In this study, gas–liquid two-phase bubble flow experiments were first carried out in a vertical upward pipeline with an internal diameter of 20 mm. A high-speed camera was used to take instantaneous snapshots of the bubbles flowing through the fluid sampler, capturing images of the size distribution of the dispersed bubbles within the fluid sampler at different flow conditions. Ultrasonic attenuation information when the bubbles flowing through the measured area was obtained using the pulsed transmission ultrasonic sensor. The magnitude and sign fractal scaling exponents of ultrasonic attenuation signals were obtained by the detrended fluctuation analysis (DFA) method, which exhibits a strong correlation with the bubble diameter. The results show that the nonlinear dynamic characteristics of bubble size evolution in gas–liquid two-phase bubble flow can be effectively characterized by ultrasonic measurement signals, which provide a crucial foundation for different bubble size of void fraction prediction model of gas–liquid two-phase flow.