Argon injection in nozzle can prevent nozzle clogging during the continuous casting process,but it can also cause defects of subcutaneous bubbles in slabs and increase the risk of intensified fluctuations at the steel-slag interface.Herein,for the process of argon injection from the bowl of nozzle,a three-dimensional mathematical model of the tundish-nozzle-mold was established by coupling the DPM model and VOF model.A 1∶2 scaled water model experiment was conducted to verify the morphology of bubble plume and size distribution of bubbles in the mold.The effects of argon flow rate,casting speed,and submerged depth of nozzle on the flow field,size distribution of bubbles in varied regions and fluctuation behavior of steel-slag interface in the mold were investigated.The results show that with a low argon flow rate,the liquid steel flowing out from the nozzle ports separates into two streams:one rushes to the narrow face,and the other impacts the steel-slag interface.Large size bubbles are mainly distributed in the near-nozzle region of the 1/2 and 1/4 wide faces.With the increase in the argon flow rate,the impacting position of the stream on the narrow face move upwards,and the slag open eyes appear in the vicinity of the nozzle and gradually become larger.Moreover,the number of large size bubbles in 1/2 wide face first increases and then decreases,and the number of small size bubbles near the narrow face increases significantly.With a low casting speed,a single-roll flow pattern is formed in the mold,and the bubbles are concentrated near the wall of the nozzle with a large slag open eye generated here.An increasing casting speed is beneficial for the uniform spatial distribution of bubbles in the mold,and reduce the area of slag open eye,but will increase the number of small bubbles in the area near the narrow face.In addition,a low submerged depth is favorable for bubbles to float upwards in the near-nozzle region.Moderately increasing the submerged depth of the nozzle can decrease the number of small bubbles near the wide face.
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