Abstract: As the last refining equipment before the solidification of the molten steel, the tundish plays an important role in improving the cleanliness of the molten steel. In order to solve the problem of poor effect of the tundish to remove inclusions, a 50 t tundish of a certain plant was taken as the target.And a 1∶4 physical model was established to study the effects of different immersion depth of long nozzle, relative distance between the weir and the dam, distance between the weir and the center of the long nozzle, and height of dam and weir on the flow fluid of the tundish. And the optimized scheme of tundish flow field was obtained by analyzing the tundish flow field and RTD curves.The results showed when the immersion depth of long nozzle was 50 mm, the relative distances between the weir and the dam was 50 mm, the distance from the weir to the center of the long nozzle was 400 mm, the height of the weir was 282 mm, and the height of the dam was 64 mm, the effect of the metallurgical effect of the tundish was the best.With the optimized scheme, the proportion of the dead zone in the tundsih was decreased and the average residence time was extended.The results of industrial application showed that the total oxygen mass fraction decreased by 16.3% and the number density of inclusions decreased by 17.1% in the slab.

Key words: tundish, flow field, the weir and dam, RTD curves, inclusions