Effect of Uniform and Non-Uniform Increasing Casting Flow Rate on Dispersion and Outflow Percentage of Tracers in Four Strand Tundishes under Strand Blockage Conditions

The flow field, tracer dispersion and uniformity of strands in two designs of four-strand tun-dishes under normal conditions and single-strand blockage conditions are studied by numerical simulation. The casting speed (flow rate) of strands are increasing uniformly or non-uniformly to improve the strand blockage condition. The uniformity of strands of the cases are evaluated by a novel outflow percentage analysis method. The results show that the flow field in the tundish does not change significantly when the single-strand is blocked or the casting flow rate is increased. After blockage of one strand, the consistency of each strand of u-shaped weir tundish is better than that of double-weir tundish. With the uniform increasing of the casting flow rate, the response time of each strand decreases and the outflow percentage increases. However, the uniformity of strands improved slightly in double-weir tundish but decreased in u-shaped tundish. For the double-weir tundish, significantly increasing the casting flow rate of the strand located in the blocked part by a factor of 1.5 and slightly increasing the casting flow rate of the other strands by a factor of 1.25, the consistency of each strand is the best. For the u-shaped weir tundish, the consistency of each strand is improved by non-uniform increasing of the casting flow rate of the strands. The flow rate of the strand located in the blocked part and the other strands is increased by a factor of 1.25, and 1.375 or 1.2 and 1.4 are the optimized cases.