| The amount of residual steel in continuous casting tundish directly affects the metal yield and production cost.With the increasing demand for diversified steel products in the market,multi-variety and small-batch customized production has become an important trend in the production of alloy steel,and the cost problem caused by the tundish residual steel will become more prominent.Therefore,it has attracted wide attention to restrain the formation of confluence vortex at the end of tundish casting,reduce the amount of residual steel,study the formation law of confluence vortex in multi-strand continuous casting tundish,and develop the suppression technology of confluence vortex.The research results are of great significance for continuous casting production,especially high value-added alloy steel continuous casting.In this paper,a physical model with a similarity ratio of 1:4 is established for a three-strand bloom tundish in a factory.Based on the study of the vortex flow characteristics of the fluid in the tundish,an optimal vortex suppression device is developed by combining physical simulation with numerical simulation.The results show that:(1)The internal structure of tundish causes the fluid flowing into the nozzle to rotate and develop continuously upward.At the end of casting,the vortex suction phenomenon first occurs at the one and three strand located at the end of tundish.The direction of the vortex above the one strand is clockwise.(2)With the increase of casting speed,the energy of molten steel at the nozzle increases,resulting in an increase in the confluence vortex at the liquid level.Under the condition of no flow control device in tundish model,the casting speed decreased from 0.65m/min to 0.48m/min,and the vortex development and penetration height decreased from 34,30mm to 20 and 17mm,which were reduced by 41%and 43%respectively.(3)The addition of the stopper can destroy the flow field of the liquid surface,improve the liquid surface stability,greatly reduce the turbulent energy,and increase the difficulty of vortex formation.At a casting speed of 0.48m/min,a stopper with a bottom distance of 20mm was added to the tundish model,and the vortex production height rise maximum,from 30mm to 20mm,which was reduced by 33%.Reducing the height of the stopper can enhance the suppression of the vortex to a certain extent.When the distance from the stopper to the bottom of the tundish is lower than the height of the development of the vortex,the effect of the suppression is significantly improved.By changing the shape of stopper,it is found that it has certain effect on vortex formation,and the elliptical stopper head has a better anti-rotation effect.(4)Compared with I-shaped and square inhibiting baffle,it is found that the two inhibiting baffles can change the flow field at the bottom of the bag and delay the vortex.However,when I-shaped inhibiting baffle is installed,the liquid flowing through the inhibiting baffle flows radially into the nozzle,which can greatly reduce the tangential velocity and vorticity near the nozzle.The effect of reducing the vortex development and penetration height is better than that of the square inhibiting baffle.(5)When the I-shaped inhibiting baffle model size L1 and L2 are 30mm and 15mm respectively,the height is 25mm,and the distance from the inhibiting baffle to the nozzle is 20mm,angle 1 arrangement is the most significant for vortex suppression.Compared to the non-flow control device,the vortex generation height is reduced by 36%,the vortex development height is reduced by 60%,and the vortex penetration height is reduced by 59%.(6)The joint arrangement of stopper and I-shaped inhibiting baffle has the best effect on the suppression of vortex.When the casting speed is 0.48m/min,the vortex generation height is reduced by 47%,the vortex development height is reduced by 60%,and the vortex penetration height is reduced by 71%.The residual steel in the tundish at the end of casting decreases greatly,and the metal yield increases obviously. |
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