Physical And Numerical Simulation On Fluid Flow In Mould Of Slab Continuous Casting

It is necessary to know and control the flow pattern of the molten steel in the mould, which is the key point to guarantee higher and more efficiency continuous casting technology and improve the quality of the products. Therefore, the flow pattern of molten steel in the mould was highly valued, the physical simulation and the numerical simulation were the most universal method. In view of the slab continuous casting mould, the flow pattern of molten steel in mould of various SEN parameter was studied by adopting the physical simulation and the numerical simulation.Utilizing the commercial software Fluent, the three dimensional mathematical model were set up according to the theory of computational fluid dynamics. The flow field and the temperature field in the mould under the conditions of different technological parameter were calculated. With the influence of immersion depth, angle of the nozzle port, the casting speed, the effect on the flow field and temperature field of the molten steel in the mould were studied. The influence on the inclusion elimination under different parameter was also discussed.The main method of physical simulation was the hydraulics simulation.1:1 scale model was established according to the similarity theory. The level fluctuation in the mould was measured by the wave probe. The influence of different technological parameters on the level fluctuation was analyzed. Using the experimental technology that was"stimulate-response", the electrical conductivity on the different position of the free surface along with the time's variation was surveyed, and the average residence time on the different position of the free surface was calculated. The flow field and the impact position in the mould were observed through adding the dyeing tracer material, and the influence of various factors on the flow field was analyzed.From the present physical and numerical simulation research, the following conclusions can be drawn: While the casting speed increasing, the level fluctuation and the jet impingement strength to the narrow wall increase, the temperature at the free surface also increases. These are benefit for the melting slag, but these are bad for the solidification of slab at narrow wall of the mould. While the submerged depth of the SEN and the outlet angle of the SEN increase, this can improve the level fluctuation and reduce slag entrapment, but this will also form the lower temperature distribution at the upper recirculation in the mould, leading to surface quality problems. The inclusion elimination rate in the mould was more influenced by the casting speed. When the casting speed was less than 1.6m/min and the inclusion diameter was larger than 350μm, the inclusion elimination effect is good. When the inclusion diameter was smaller than 100μm, the elimination rate was lower than 20% under different casting parameters. It is proved that the smaller the diameter inclusion is the more difficult to remove in the mould. When the inclusion diameter was larger than 400μm, the elimination rate may achieve above 80% under different casting parameters. These explain that mould was good to eliminate the inclusion with larger diameter. For the 1250×230mm~2 slab caster, the chosen optimal technological parameters are: the downward 15 deg port angel of the SEN,1.6-1.8m/min of the casting speed, 180-250mm of the submerged depth of the SEN and 10-20L/min of flow rate blowing.