Article ID: ISIJINT-2016-670
The bubbling in liquid steel can improve steel cleanliness effectively. To understand the single bubble behavior and the interactions between two bubbles, which are basis to analyze the mechanism of gas-liquid two-phase flow in metallurgical vessel, the bubbling at a laminar flow has been systematically studied by both water-model experiment and three-dimensional numerical simulation. Nozzle diameters of 1.5, 2, and 2.5 mm were investigated within a certain range of gas flow rate. The images of bubbles emerging from the nozzle were observed by the water-model experiment. The volume of fluid (VOF) model in conjunction with continuum surface force (CSF) model was used to describe the interface between the gas and liquid on the software platform of Fluent 14.5. The phenomena of bubbling, rising motion, coaxial bubbles coalescence and parallel bubbles bounce with one- and two-nozzle were found in air-water and argon-steel system. The initial bubble sizes increase with increasing gas flow rate or nozzle size, whereas is relatively independent of the nozzle size when gas flow rate is 0.975 L/min. The terminal velocities of all bubbles are around 0.32 m/s. The evolution history of bubble shape changes from non-deformed (spherical) to the deformed shapes (spherical cap, ellipsoidal, wobbly or ellipsoidal cap) without coalescence. Calculated velocity and pressure distributions indicated that the rising velocity of the trailing bubble is larger than that of the leading bubble, which result in two coaxial bubbles coalescence. The small eddies on the inner edge of two parallel bubbles eventually lead to bubbles bounced each other.
