Lage Tord Ingemar Jonsson

The effect of the immersion depth of a new swirling flow tundish SEN (Submerged Entry Nozzle) on the multiphase flow and heat transfer in a mold was studied using numerical simulation. The RSM (Reynolds Stress Model) and the VOF (Volume of Fluid) model were used to solve the steel and slag flow phenomena. The results show that the SEN immersion depth can significantly influence the steel flow near the meniscus. Specifically, an increase of the SEN immersion depth decreases the interfacial velocity, and this reduces the risk for the slag entrainment. The calculated Weber Number decreases from 0.8 to 0.2 when the SEN immersion depth increases from 15 cm to 25 cm. With a large SEN immersion depth, the steel flow velocity near the solidification front, which is below the mold level of SEN outlet, was increased. The temperature distribution has a similar distribution characteristic for different SEN immersion depths. The high temperature region is located near the solidification front. Temperature near the meniscus was slightly decreased when the SEN immersion depth was increased, due to an increased steel moving distance from the SEN outlet to the meniscus.

The effect of a new cylindrical swirling flow tundish design on the multiphase flow and heat transfer in a mold was studied. The RSM (Reynolds stress model) and the VOF (volume of fluid) model were used to solve the steel and slag flow phenomena. The effect of the swirling flow tundish design on the temperature distribution and inclusion motion was also studied. The results show that the new tundish design significantly changed the flow behavior in the mold, compared to a conventional tundish casting. Specifically, the deep impingement jet from the SEN (Submerged Entry Nozzle) outlet disappeared in the mold, and steel with a high temperature moved towards the solidified shell due to the swirling flow effect. Steel flow velocity in the top of the mold was increased. A large velocity in the vicinity of the solidified shell was obtained. Furthermore, the risk of the slag entrainment in the mold was also estimated. With the swirling flow tundish casting, the temperature distribution became more uniform, and the dissipation of the steel superheat was accelerated. In addition, inclusion trajectories in the mold also changed, which tend to stay at the top of the mold for a time. A future study is still required to further optimize the steel flow in mold.