Relationship Between Fluid Flow Stability and Submerged Entry Nozzle Port Angle in a Conventional Slab Continuous-Casting Mold

Fluid flow patterns within a conventional slab continuous-casting mold are closely linked to the port angle of the submerged entry nozzle (SEN). Fluid flow is unstable below a certain port angle, with large fluctuations near the port outlet as well as jet stream oscillation and repeated vortex formation and dissipation within the mold. However, such phenomena are not observed above a certain port angle, at which the flow pattern becomes stable. This behavior was investigated via both numerical simulation and water model experimentation; two different regions were identified with flow patterns varying according to the SEN port angle. In addition, a close quantitative relationship was identified between changes in the port angle and fluid velocity variations. For SEN port angles in the range 0°–15°, the flow velocity in the upper circulation zone oscillated in an unstable manner. For port angles of 20° or more, the flow velocity of the same zone decreased significantly and stabilized. When the gas was injected, the unstable region elongated to 0°–20°. The present study offers insight toward developing a clearer understanding of the complex flow patterns in casting molds, as well as of the conditions necessary for stable flow patterns.