Some Aspects on Macroscopic Mixing in a Tundish

Sammanfattning: Two aspects on macroscopic mixing in a continuous flow system – metallurgical tundish were studied. Specifically, 1) the first focus was on salt solution tracer mixing, which is important for tundish design from perspectives of tracer technology and Residence Time Distributions (RTD) as well as for the understanding of the macroscopic mixing in tundishes. The different amounts of salt solution tracer mixing in a tundish were studied by using both physical models and mathematical models. The disturbance of KCl salt tracer on the flow in the tundish with respect to different amounts is like the “butterfly effect”, i.e. only a slight increase of the amount of tracer, the flow field might be disturbed. This, in turn, will result in a shifted RTD curve. 2) The second focus was on Eulerian modeling of inclusions macroscopic transport and removal, which is important for tundish design from perspectives of inclusions removal and to provide information of macroscopic removal of inclusions. In the study, an approach that combined the meso-scale inclusions deposition at turbulent boundary layers of steel-slag interface and the macroscopic transport of inclusions in the tundish was used. The theoretical calculation results showed that the effect of the roughness on the deposition velocity of small inclusions (radius of 1 ?m) were more pronounced than that for the big inclusions (up to the radius of 9 ?m). The dynamic inclusions removal studies showed that the tundish with a weir and a dam exhibited a better performance with respect to the removal of bigger inclusions (radii of 5 ?m, 7 ?m and 9 ?m) than that of the case without weirs and dams. However, the tundish without weirs and dams showed a higher removal ratio of smaller inclusions (radius of 1 ?m).