Steel Alloy Homogenization During Rheinsahl-Heraeus Vacuum Treatment: Conventional Computational Fluid Dynamics, Recurrence Computational Fluid Dynamics, and Plant Observations

Computational fluid dynamics (CFD) simulations of steel flow in an Rheinsahl-Heraeus (RH) process are realized by a discrete phase model (DPM) for the driving bubble plumes, a volume of fluid (VoF) method for the free surface in the vacuum chamber (VC), and a large eddy simulations (LES) model for the transport and mixing of steel alloys. CFD simulations are opposed to particle image velocimetry (PIV) analyses of flow pattern at the bath surface in the VC. While simple Reynolds averaged turbulence models fail to reproduce these plant observations, LES agrees fairly well. Furthermore, the steel recirculation rate is compared with empirical correlations from the literature, yielding good agreement with respect to the dependency of the recirculation rate on the gas injection rate. The absolute value of the recirculation rate increases by 15%, in case (realistic) eroded edges are considered instead of a (unrealistic) sharp-edged geometry. Data-assisted recurrence CFD (rCFD) is applied to accelerate conventional CFD. The rCFD simulations yield a computational speed-up of four orders of magnitude, enabling real-time LES at full grid resolution of three million cells. Titanium homogenization in the steel ladle is addressed by means of rCFD and compared with corresponding plant trials yielding good agreement.