Visualization of bubbly flows injected by a top submerged lance (TSL) in a liquid metal layer by X-ray radiography

We report laboratory experiments focusing on bubbling phenomena arising from gas injection through a top submerged lance (TSL) in a liquid metal layer. Visualization was performed in the eutectic alloy GaInSn using X-ray radiography. Argon bubbles were injected through the nozzle positioned at three different submergence depths. The spatial distribution of time averaged void fraction was obtained by image processing for two-dimensional projected images. The results show that the deep position of the submerged lance causes an asymmetric large-scale circulation inside the fluid vessel. Bubbling frequencies were calculated by fast Fourier Transformation from fluctuations of the image brightness in the vicinity of the nozzle injection point. The frequency is not changed for variations of the gas flow rate and the submergence depth of the nozzle. An increasing gas flow rate results in an increasing size of the gas bubbles and mean bubble velocities.