Analogous Water Modelling of an Asymmetric Multiple Strand Tundish Using Turbulence Inhibitors and Bubble Diffusers

The main function of the tundish is to constantly provide molten steel to each strand, for which it is important to determine the uniformity of residence times, particularly in multiple-strand tundishes. In this study, the residence time distribution, minimum and maximum concentrations, and active and dead volume fractions were determined in a 5-strands asymmetric tundish equipped with turbulence inhibitors and argon curtains. Physical modelling was used as a tool, for which a 1:3 reduced-scale analogous water model of the prototype tundish was designed and constructed. For the experimental analysis four cases were studied, the stimulus-response technique was used, in which an inert tracer (HCl) was injected as a pulse at the ladle shroud, the change in the water conductivity was measured at each of the strands, the minimum residence times and the times at which the concentration was maximum were measured and recorded, and the residence time distribution (RTD) curves were plotted; a mixed model was used to characterize the active flow volume fractions (piston and mixed) and dead volume fraction. From the analysis and discussion of the results, no uniformity was observed in any of the four cases studied for the maximum concentration time. The hexagonal turbulence inhibitor alone achieved a result very similar to that of the arrangements with argon diffuser in their characteristics and flow distribution. The use of argon diffusers is recommended to improve the cleanliness of steel.