Turbulent flow of liquid steel and argon bubbles in slide-gate tundish nozzles: Part I. Model development and validation

The quality of continuous-cast steel is greatly affected by the flow pattern in the mold, which depends mainly on the jets flowing from the outlet ports in casting with submerged tundish nozzles. An Eulerian multiphase model using the finite-difference program CFX has been applied to study the three-dimensional (3-D) turbulent flow of liquid steel with argon bubbles in slide-gate tundish nuzzles. Part I of this two-part article describes the model formulation, grid refinement, convergence strategies, and validation of this model. Equations to quantify average jet properties at the nozzle exit are presented. Most of the gas exits the upper portion of the nozzle port, while the main downward swirling flow contains very little gas. Particle-image velocimetry (PIV) measurements are performed on a 0.4-scale water model to determine the detailed nature of the swirling velocity profile exiting the nozzle. Predictions with the computational model agree well with the PIV measurements. The computational model is suitable for simulating dispersed bubbly flows, which exist for a wide range of practical gas injection rates. The model is used for extensive parametric studies of the effects of casting operation conditions and nozzle design, which are reported in Part II of this two-part article.