Numerical Simulation on Multiphase Flow and Slag Entrainment During Casting Start of a Slab Continuous Casting Tundish

In the current study, a three-dimensional mathematical model combining the realizable k–ε turbulent model, volume of fluid (VOF) multiphase model, and heat transfer model was established to investigate the steel–slag–air multiphase flow, slag entrainment, adding and spreading of the slag, and temperature distribution of the molten steel and refractory during the casting start of a slab continuous casting (CC) tundish. The influence of the natural convection induced by the temperature gradient on the fluid flow was considered. The effect of the structure of turbulence inhibitor on the flow pattern in pouring area, air entrainment, and surface-level distribution was compared and discussed. The residence time distribution (RTD) of a water model was used to validate the current mathematical model. The relationship between the pouring speed and the area of the open eye was proposed and the dimensionless open eye area can be expressed in terms of Froude number ( U p / gH ), density ratio ( ρ slag /Δ ρ ), and Reynolds number ( HU p / ν slag ) via : 1 A_es/hH = k ·[ ( U_p - a)^2/gH]^1.28b·( ρ_slag/Δρ)^0.55·[ ν_slag/H( U_p - a)]^ - 0.05 where A es is the eye area, m 2 ; H is the slag layer thickness, m; h is the steel depth, m; U P is the average plume rise velocity, m/s; the coefficient of correction k, b, and a is 1.09, 0.9, and 5.86, respectively. The average temperature of the molten steel was decreased by 1.2 K after the adding of the slag. No open eye would be formed when the pouring velocity was less than 0.9 m/s. The greater the average turbulent kinetic energy of the molten steel, the higher spreading speed of the slag and the more mass of the entrained slag.