Study On Asymmetric Flow Field Of Molten Steel In CSP Thin-slab Continuous Casting Mold

As the most important part of continuous casting equipment,the reasonable flow field and liquid level fluctuation inside the mold not only make use of the formation of solidified shell,but also benefit the melting of mold powder,which plays a vital role in the quality of slab and the smooth running of continuous casting.For CSP thin slab continuous casting and rolling,because of the narrow inner space of the mold,the slab thickness at the outlet of the mold is smaller,and the casting speed is higher,the internal flow field of CSP thin slab continuous casting and rolling is more susceptible to the changes of drawing speed,nozzle immersion depth,nozzle nodulation and nozzle bias.Therefore,it is of great significance to study the flow field,liquid level velocity and liquid level fluctuation of molten steel in CSP thin slab continuous casting mold after these factors change.In this paper,the molten steel in the mold of CSP thin slab continuous casting in a steel plant is taken as the research object,according to the calculation of liquid steel in the mold to make reasonable assumptions,using the flow field and temperature field differential equation and the single valued condition to establish the ideal state of continuous casting,the gate of nodules and gate bias flow field,temperature field mathematical model,by using the VOF model building steel slag distribution calculation model,numerical calculation using the Fluent software modules.Firstly,the flow field,temperature field and liquid surface velocity at different casting speed and different immersion depth are calculated under the ideal condition of nozzle without nodulation.The results show that the flow field of CSP crystallizer with a bovine nose nozzle is typical of two upper and two lower reflux zones.And the temperature of molten steel at the vortex center is lower;with the increase of billet drawing speed,the liquid surface velocity increases;with the increase of immersion depth,the liquid surface velocity decreases.Secondly,according to the actual situation in the continuous casting process,the flow field,liquid level fluctuation and steel liquid level velocity at the outlet with different nodulation rates on one side of the nozzle were calculated.The influence of the change of one of the factors,such as the casting speed,the depth of the nozzle and the width of the billet,on the flow field,the fluctuation of the liquid level and the velocity of the liquid level of the steel,was calculated when the oneness rate of the nozzle was 35%.The flow field and velocity of molten steel in two typical cases of nozzle without nodule but with nozzle offset of 3%(45mm)and 5%(75mm)respectively are calculated.Finally,according to the results of the study,the influence of various factors on the flow field of molten steel in the mold and whether slag entrapment will occur at the molten steel level are given.