Study On Structure Optimization Of The Swirling Chamber In The Swirling Flow Tundish

The optimal design of the flow-control device in the continuous casting tundish is of great significance to improve liquid steel flow and extend the residence time.At present,domestic and foreign steel companies have taken many technical measures including installing turbulence controllers and applying centrifugal chamber in tundish.Based on the design principles of traditional turbulence controllers and centrifugal chamber,investigators in the related field proposed a solution called swirling flow tundish.In the swirling flow tundish,the traditional straight long nozzle is still used.In recent years,during the promotion of the swirling flow tundish technology,it has been found that the precise docking of the straight long nozzle and the swirling chamber is quite difficult in actual operation.A little carelessness may lead to production accidents.In this context,the current study presents a scheme of using a special-shaped drafting nozzle with a straight cylindrical swirling chamber to solve the above-mentioned docking problem.This therefore requires research work to carry out structural optimization of the special-shaped spouted long nozzle and the straight cylindrical swirling chamber.In this study,the numerical calculation of the flow field in the swirling flow tundish is firstly performed.The flow field in the swirling chamber and the injection area is analyzed.Also,the calculation of the residence time distribution of liquid steel and numerical simulation of slag entrapment are conducted.The effects of different structure parameters of th swirl chamber on the flow field,residence time of liquid steel,and behavior of slag entrapment under the condition of fixed structure and position of the special-shaped nozzle are examined.The main conclusions obtained in this study are as follows.(1)Through the analysis of the flow field in the injection zone,an inverse flow is generated on top of the swirling chamber when liquid steel leaves the swirling chamber.The intensity of the inverse flow decreases with an increase in the height of the swirling chamber or in the diameter of the swirling chamber.(2)With the diameter of the swirl chamber being 0.5 m,the average residence time of liquid steel reaches a maximum value of 894 s when the height of the swirling chamber is 0.35 m.Compared with the chamber without swirling flow,the average residence time is increased by 18 s;When the diameter of the swirling chamber is 0.625 m,the average residence time of liquid steel reaches a maximum value of 894 s when the height of the swirling chamber is 0.35 m.Compared with the chamber without swirling flow,the average residence time is increased by 18 s.When the chamber diameter is 0.75 m,the average residence time of liquid steel reaches a maximum value of 899 s when the height of the swirling chamber is 0.65 m,and the average residence time is increased by 23 s.(3)When the diameter of the swirling chamber is 0.75 m and the height is 0.65 m,the ratio of the fraction of mixed flow to the one of the dead zone is the largest on the basis of the simple combined model.(4)Under the condition of the same swirling chamber diameter,as the height of the swirling chamber increases,the entrapment pit of slag becomes deeper.Therefore,slag entrapment can be alleviated by decreasing the height of the swirling chamber.(5)Under the same swirling chamber height,as the diameter of the swirling chamber increases,the entrapment pit of slag becomes deeper and then shallower,and the area of the entrapment pit becomes bigger.Therefore,slag entrapment can be suppreWhen the diameter exceeds a certain value,light slag can be alleviated by by increasing the diameter of the swirling chamber.