Mathematical modeling of the effect of SEN outport shape on the bubble size distribution in a wide slab caster mold

Herein, the effects of outport shapes of the submerged entry nozzle (SEN) on the size distribution of argon bubbles were studied in a wide slab caster mold by the mathematical modeling. The Eulerian–Eulerian model coupled with Multiple-Size-Group (MUSIG) approach were used to solve equations of the two phase flow and polydispersed bubbly flow in the mold, respectively. The effect of the SEN outport angle and shape on the distribution of the molten steel flow, argon gas volume fraction, and argon bubble size were investigated. The outport shapes of the SEN included large rectangular, small rectangular, square, trapezoid, and runway. Results showed that the speed of molten steel increased within the range of 260 mm from the SEN, and decreased within the range of 550 mm from the narrow face with the outport angle of SEN increased from 20° to 45°. The bubble diameter was 5.7 mm at 255 mm distance from the SEN along the mold width at different outport angles. The average speed of molten steel at the outport of SEN decreased from 0.91 to 0.72 m/s with the outport shape changed from small rectangular to runway, trapezoid, square and large rectangular. The average diameter of bubbles was approximate 5.2 mm at the outport for the five types of nozzles, and increased from 3.2 to 3.45 mm inside the mold with the outport shape changed from the runway to square, trapezoid, large rectangular and small rectangular, indicating the rate of bubble breakup was larger with the runway and square SEN casting.