Development of flow field and temperature distribution during changing divergent angle of the nozzle when using swirl flow in a square continuous casting billet mould

Recently, positive effects of swirl flow have been investigated, related to specific billet moulds with particular divergent angles in the immersion nozzles. (1-7)) Literature review showed that a systematic study of changes in the divergent angle in the immersion nozzle for continuous casting moulds had not been carried out. Therefore, in the present work we aim to investigate the development of flow field and temperature distribution inside the mould and on the meniscus while changing the divergent angle of the immersion nozzle. Swirl flow was used in the nozzle and the liquid entered a 3D square billet mould. Both physical and mathematical modelling was carried out to simulate nine different divergent angles between 0 and 160 degrees. The overall results of the study showed that a change in divergent angle has an effect on the flow pattern as well as the temperature distribution of the liquid steel in the mould. More specifically it was found that in the case of 100 degrees divergent angle nozzle billet we can observe a major shift of lower circulation compared to that of the 80 degrees nozzle billet. Furthermore, a noticeable increase of the temperature near the meniscus, for a square billet, and radial velocity component, for a round billet, was found when using the 100 degrees divergent angle nozzle compared to the 80 degrees divergent angle nozzle. Additionally, a uniform velocity and heat distribution was observed within a distance of 200 mm below the nozzle exit for nozzle outlets with 100 degrees divergent angles and larger.