Simultaneous measurement of bubble size, velocity and void fraction in two-phase bubbly flows with time-resolved X-ray imaging

Key parameters of two-phase flows, such as void fraction and microscale bubble size, shape and velocity, were simultaneously measured using time-resolved X-ray imaging. X-ray phase-contrast imaging was employed to obtain those parameters on microbubbles. The void fraction was estimated from X-ray absorption. The radii of the measured microbubbles were mostly smaller than 20 µm, and the maximum velocity was 39.442 mm s⁻¹, much higher than that in previous studies. The spatial variations of the void fraction were consecutively obtained with a small time interval. This technique would be useful in the experimental analysis of bubbly flows in which microbubbles move at high speed.