Original Article

Numerical simulation on multiphase flow and steel grades mixing in a slab continuous casting tundish

School of Mechanical and Materials Engineering, North China University of Technology, Beijing 100144, China

^* e-mail: weichen@ncut.edu.cn
^** e-mail: zhanglifeng@ncut.edu.cn

Received: 26 September 2024
Accepted: 22 November 2024

Abstract

Four comprehensive numerical models, including the Volume of Fluid (VOF), Mixture, Eulerian, and Species, were established to explore the multiphase flow and replacement of old steel grades with new ones during the continuous casting of different grades in a slab tundish. A water model was employed to validate the accuracy of the numerical model. The result shown that the VOF multiphase model and standard k-ε turbulence model were specifically utilized to analyse the complex four-phase flow dynamics involving the new molten steel, old molten steel, slag, and air. Moreover, the effect of varying casting speeds on the replacement process, mixed casting slab length, and molten steel exposure time were performed. With constant emptying times, an increase in casting speed led to a reduction in replacement liquid level and lower residual old steel content, shortening the mixed slab length. However, higher speeds required longer refilling periods, consequently intensifying the exposure of molten steel and potentially affecting steel quality. At a casting speed of 1.7 m/min, the exposure time of the molten steel was 82.6 s, and the mixed casting slab length was 5.78 m. At a casting speed of 1.1 m/min, the exposure time was dropped to 42.5 s, while the mixed casting slab length was increased to 13.02 m. Considering both steel mixing and its exposure behaviour, a casting speed of 1.4 m/s was considered more suitable, ensuring an appropriate mixed casting slab length and maintaining the quality of molten steel.