Model Experimental Research On Flow And Behavior Of Bubbles In Mold For Slab Continuous Casting With Swirling Flow

In continuous casting process of steel, the occurrence of uneven outlet flow from SEN is unavoidable, which leads to uneven distribution of the flow field and temperature field and to the meniscus fluctuation in the mold and so on, It influences the surface and internal quality of the billet as well as the casting speed. The swirling flow in SEN is effective to control the occurrence of bias. In the preceding research a new process was proposed, in which a rotating electromagnetic field was set up around a SEN to induce swirling flow of molten steel by Lorentz force. The simulating and preliminary experimental works on magnetic field induced by different types of electromagnetic swirling flow generator (EMSFG) and flow field in different molds were carried out.In this paper, hydromechanical model experiment for slab continuous casting with swirling flow was carried out, the effect of different process parameters (swirling and horizontal rotation angle of nozzle, type of nozzle, argon blowing) on liquid flow field and bubble behavior in slab mold was studied. The flow field in mold was investigated by tracer and camera; in velocity measurement, the two-dimensional velocity distribution was acquired by Doppler velocimetry (UDV), the effect of swirling and argon on flow field was analyzed; bubble behavior in mold was recorded and studied by high-speed video camera. Summed up the following main conclusions:1. Swirling flow decreases the angle between flow discharged from the nozzle and enhances the mixing of the flow in mold.2. In the case of swirling, the outlet flow impinges on the wide face and then turns around as a reverse flow along the other wide face. If the nozzle rotates to a certain angle horizontally, this impingement phenomenon disappears.3. In the case of argon blowing and no swirling:the horizontal velocity of the outlet of convex bottom nozzle decreases, the horizontal velocity of the outlet of concave bottom nozzle increases; the horizontal velocity of downward streams decreases, the horizontal velocity of upward stream increases significantly, the vortices center of upward flow disappears.4. In the case of argon blowing and swirling with the nozzle rotating to a certain angle: Nothing to do with the type of the nozzle shape, the horizontal velocity of the outlet decreases, the horizontal velocity of downward stream decreases, the horizontal velocity of upward stream increases significantly; the vortices center of upward flow rises for the convex bottom nozzle and the vortices center of upward flow disappears for the concave bottom nozzle.5. Bubbles penetration depth increases in the vertical direction and goes farther in the horizontal direction by swirling flow.