Numerical simulation of swirling flow in divergent submerged entry nozzle in round billet continuous casting of steel

Abstract

With the development of continuous casting technology, the quality of billet has been paid more and more attention recently. It is very important in continuous casting to strictly control the cleanliness of molten steel, and to reduce the defects of billet. The control of flow pattern of molten steel in mold is one of the important means to increase casting efficiency and improve billet quality. Swirling flow in the submerged entry nozzle (SEN) has great effect on improving the uniformity and stability of the outflow from the nozzle in continuous casting of steel process. A new process for swirling flow generation in the SEN has been proposed. That is a rotating electromagnetic field is set up around the SEN to induce swirling flow in it by Lorentz force. In this research, the flow and temperature fields in the SEN and round billet mold with electromagnetic swirling are numerically simulated. The effects of the divergent angle of the SEN with electromagnetic swirling on the flow and temperature fields in the mold are investigated. The simulated results show that, with the increase of the coil current intensity, the magnetic flux density and the swirling flow velocity in the SEN increases. The largest swirling flow velocity in the SEN can reach about 3 m/s in coil current intensity 500 A, frequency 50 Hz. In a divergent angle of the SEN, such as 60°, when the coil current intensity increases, the impinging depth of the outflow from the nozzle reduces, the upward flow velocity and the meniscus temperature increase. While the coil current intensity increases larger than 350 A, the meniscus temperature changes little. In a certain intensity of swirling flow, such as 350 A, 50 Hz, when the divergent angle of the SEN increases, the upward flow velocity and the meniscus temperature firstly increase and then decrease. In divergent angle 60°, the upward flow velocity and meniscus temperature get the largest value. In a divergent angle 60°, coil current intensity 350 A, frequency 50 Hz, with an artificial uneven flow of 0.5 m/s horizontal velocity at the inlet of the SEN, the uneven flow can be suppressed effectively. © right.