Simulation Research On Behavior Of Molten Steel Flow And Level Fluctuation In Slab Mould

In recent years, with the developments of iron and steel industry and the increasing enhancement of products quality in our country, it is more and more important to optimize continuous casting technology; the product quality mainly depends on the controlling of steel cleanliness and casting strand surface and inner disfigurement, while the mold operation is just the last procedure. In the process of slab continuous casting, the melt steel flow fluid in the mold has a great influence upon heat transfer and inclusions floatation, also with many surface and inner quality problems such as crack, segregation etc. Reasonable flow field and level fluctuation of molten steel in the mold may result in reducing some inner defects, such as slag entrapment, argon bubbles, cracks, and so on. Therefore it is very importance to study and control the flow field and level fluctuation of molten steel in the mould for improving the surface quality of casting strand.The traditional water model can not research the previous phenomena completely because of the complexity and closeness of metallurgy process, but using numerical simulation to research has been a key method. The archetype of the mold is the slab continuous casting mold (cross section size is 1280mm×180mm) of an iron and steel company in china. An"air- molten steel"two phase flow model is established by the commercial software Fluent; molten steel flow field and level fluctuation in the mold are simulated applying k-εturbulence model and volume fraction method. It is investigated that the technique parameters, including the immerging depth of the submerged entry nozzle (SEN), angle of the nozzle port, the casting speed and width of the mould, effect on the flow field and level fluctuation of the molten steel in the mould.We did not consider the free surface before and used to consider slip wall or symmetry. In this research, we use the VOF model to analyze the unavoidable free surface. From the present numerical simulation research, the following conclusions can be drawn:(1) The behavior of molten steel flow in the mould is"Double Roll", the bigger velocity of steel from the nozzle port impacts the narrow face nearly with linear, and then the narrow face occurs up-backflow and down-backflow.(2) The VOF can accurately simulate the level fluctuation of the free surface, and the casting process in the mould is a non-steady process with up-down periodical fluctuation.(3) While the casting speed increasing,the velocity of steel in the mould and the level fluctuation also increase. While the submerged depth of the SEN and the outlet angle of the SEN increasing, this can improve the level fluctuation and reduce the fluid penetration depth, and not help the inclusions floating advantageously. With the width of the mould increasing, the disturbance of steel in the mould and the level fluctuation also increase.