X-ray visualisation of bubble formation and bubble motion in liquid metals

The real-time digital X-ray radioscopy has been used to visualise the liquid metal two-phase flow in a GaInSn melt in a flat container with a rectangular cross-section. Argon bubbles were injected through single orifices at the side-walls of the fluid vessel. X-ray images were acquired with a frame rate of 22.3 Hz. Exposure times of 5 ms deliver instantaneous snapshots of the flow structure. Quantitative values of the mean bubble size, bubble velocity, bubble distribution and bubble trajectory were obtained from the X-ray data. It was shown for the liquid metal case that the wetting conditions at the gas injector significantly affect the size of the detaching gas bubbles.