Modeling of Fluid Flow and Residence Time Distribution in a Four-strand Tundish for Enhancing Inclusion Removal

摘要

The introduction of the appropriate size and precise location of flow control devices such as dam, turbulence inhibitor, etc., helps to modify the flow pattern and minimizing short circuiting and dead zone. Beside this, these also create the surface directed flow and maximize the residence time available for the flotation of inclusions and assimilation of the reaction products from the molten steel into the slag phase. These can be products of deoxidation, reoxidation, precipitation, emulsification and/or entrainment of refractory components into the melt and thus encompass both indigenous and exogenous inclusions. To this end, both the numerical and physical simulations were carried out mainly for three cases: a) in absence of flow control devices (i.e., bare tundish), b) in the presence of a dam, and c) with the application of turbulence inhibiting device (TID) and dam combination in the existing tundish configuration. The commercial CFD (computational fluid dynamics) package FLUENT® was used to predict the flow field prevalent in the water model tundish at steady state, whereas in the experimental program, both Particle Image Velocimetry (PIV) techniques for flow measurements and tracer dispersion experiments for concentration measurements were applied in the present study. Among all types of configurations applied in the present study, a combination of TID with holes+a dam work reasonably found to be an optimum configuration of the four-strand tundish regarding inclusion floatation. A superior strand similarity is also achieved in this configuration. Also the predicted time averaged horizontal and vertical components agreed within±10% with the experimentally derived ones.