Effect Of Process Parameters On Argon Bubbles Behavior In Slab Mold With Electromagnetic Swirling Flow In Nozzle

The swirling flow in a submerged entry nozzle(SEN) is effective on improving the uneven flow in the nozzle, and greatly improve the surface and internal quality of casting billet as well as casting speed. Fundamental research result shows that, electromagnetic swirling flow also can generate swirling flow in the nozzle. In this paper, rotating electromagnetic field and electromagnetic force in the SEN under the swirling generator is simulated with EMAG module of ANSYS code. The electromagnetic force is imported into FLUENT code for the flow field calculation in the slab mold. Effect of four process parameters:the SEN immersion depth, the upper wall radius of the nozzle outlet port, the casting speed, the width of the nozzle outlet port on the flow field in the slab mold are analyzed. Then the coupling calculation of the flow field and the argon bubble behavior (trajectory and concentration distribution) is conducted with Lagrange dispersed phase model. The effects of these parameters on the argon bubble behavior are studied.Conclusions are as follows:1.With the electromagnetic swirling, the mainstream flow from the outlet of the nozzle is no longer parallel to the wide face of the mold, but impinges on the wide face, forming an upward flow and a downward flow. The maximum velocity on the nozzle outlet port appears at the upper part. The velocity on the meniscus decreases. With the argon gas blowing, the bubble is carried by the swirling flow which impacts to the wide face of the mold, and the distribution of bubble becomes uniform along the wide face. There are more bubbles near the wide face in the downstream side of the swirling flow, then the bubbles float to the meniscus because of the buoyancy.2.With the SEN immersion depth increases, the upward flow region becomes larger, the vortex center moves down and the velocity on the meniscus decreases; with the argon gas blowing, due to the increase of the immersion depth, the impact depth and the movement range of bubbles in the mold become larger, there are more bubbles carried to the narrow face.3.With the increase of the upper wall radius of the nozzle outlet port, the vertical angle of the outlet flow from the nozzle becomes larger, the outlet flow impacts deeper slightly, velocity on the meniscus decreases slightly; with the argon gas blowing, there are more bubbles carried to the narrow face in the mold because of the deeper impact of the flow.4.With the casting speed increases, the upward flow and the downward flow become stronger, the velocity on the meniscus becomes larger, maximum velocity on the nozzle outlet port moves downward. In the case of low casting speed, bubbles float up in the vicinity of the SEN. In the case of high casting speed, the movement range of the bubbles become larger in the mold, there are more bubbles carried to the narrow face in the mold, some bubbles even carried to the downward flow.5. With the width of the outlet port increases, the horizontal deflection angle of the outlet flow from the nozzle (impinge on the wide wall) becomes larger, the velocity on the meniscus decreases; with the argon gas blowing, there are more bubbles carried to the narrow face in the mold.