Effect of Nozzle Angle on Flow Field and Temperature Distribution in a Billet Mould when using Swirl Flow

Abstract

Recently, interesting effects have been noted in studies of swirl flow, particularly regarding billet moulds when considering a specific divergent angle of the immersion nozzle. Therefore, in the present work a numerical analysis and water model study of the mould region of a continuous casting apparatus are performed with changing the outlet divergent angles of the immersion nozzle using swirling flow in the pouring tube, to control the heat and mass transfer in the continuous casting mould. To make our studies consistent with the previous research, which was done based on a square billet, this time we investigate round billets. The results show that the distance from the meniscus of the centres of both the lower and upper circulation loops decreases systematically with increasing the divergent angle. This, in turn, leads to: (i) a more active heat and mass transport near the meniscus (particularly over 100°); (ii) a gradual change from a concentric circulation to a more clearly logarithmic spiral from the mould wall to the nozzle on the meniscus, which leads to more active heat and mass transfer; (iii) a decreased penetration depth of nozzle outlet flow (even at a comparatively small divergent angle such as 20°) and a superheat dissipation in the melt.