Abstract: In order to reduce the interface energy consumption during the casting-rolling process of high-quality low-carbon steel, the No.2 continuous casting machine at Meishan Steel implemented a transformation from a two-strand to a single-strand tundish. This modification increased the casting speed from 1.2 m/min to 2.4 m/min, enabling single-strand high-speed casting production. A combined approach of physical and numerical simulations was employed to investigate the flow characteristics and inclusion trajectories under different operating conditions. The results demonstrated that the original flow control devices of the tundish were no longer suitable for single-strand casting after modification, leading to significant dead zones (particularly on the blocked-strand side) and poor mixing homogeneity. By introducing a novel turbulence inhibitor and redesigned dam, the flow pattern on the blocked-strand side was notably improved. The dead zone volume decreased by 12.2%, the response time extended by 96.7%, the average residence time increased by 11.2%, and the peak concentration decreased by 45.3%, indicating superior flow field uniformity in the optimized tundish. The removal efficiency of inclusions was significantly enhanced in the modified tundish. The results of large sample electrolysis revealed that the average inclusion content decreased from 0.78 mg/kg (original configuration) to 0.29 mg/kg (optimized configuration). The implementation of new flow control devices effectively improved flow patterns in the tundish， enhanced the removal efficiency of inclusions and the cleanliness of molten steel, significantly increased the casting speed of the continuous casting machine, and assisted in energy-saving and carbon reduction in steelmaking.

Key words: two-strand tundish, single-strand casting, inclusions, flow field, large sample electrolysis