Effect of Orifice Position on Bubble Aggregation and Coalescence in Dynamic Rotating Flow

Implementing contact bubble refining techniques in high-temperature metallurgical and material preparation processes is challenging. It reduces the efficiency of mass and moment transfers due to the presence of large bubbles in the molten metal. Here, an innovative attempt to minimize the size of the bubbles by velocity fluctuation is suggested. An experiment was undertaken in water to visually investigate the size of the bubbles, and it was observed that an increase in velocity fluctuation facilitates the ability of turbulent stress to break the bubbles into smaller bubbles. Furthermore, the drag force induces an oblique ascent of the mother bubbles, extending the separation between them. By decreasing the time and probability of contact between the mother bubbles, aggregation and coalescence are inhibited. Finally, the number of bubbles increases by almost 500 compared to that observed in the stagnant liquid. The average mean diameter and Sauter mean diameter of the bubbles reduced by 54.66% and 58.27% to 3.94 mm and 4.92 mm, respectively. By substantially improving the interactions between the molten metal and the bubbles, this work reports an effective method to improve the quality and production efficiency of molten metal.