Experimental simulation and mathematical modeling of air bubble movement in slab caster mold

Abstract

Experimental simulation of air bubble movement in a 1/3rd scale model slab caster mold has been done for parallel, upward and downward port submerged entry nozzle (SEN) with different water flow and air flow rates in order to study the bubble penetration depth, horizontal dispersion and the air jet angle. It has been observed that the bubble penetration depth depends more on the flow rate of water rather than that of air. The bubble penetration depth also depends on the port angle and on the "well" provided on the SEN. Below a certain critical water flow rate the flow becomes asymmetric in the slab caster mold for a given flow rate of air. SEN with a well depth may help to avoid bubble entrapment defects in the slab at the cost of higher surface disturbances on the mold. A mathematical modeling of the air bubble movement in water was also carried out for the same experimental set up where it was observed that for same air flow rate the bubble penetration depth was more for higher water flow rate confirming to the experimental findings. The experience gained from the experiment and mathematical modeling helped to fine tune the parameters at the caster so that the strike rate of ultra low carbon grade steel could be improved substantially. © 2006 ISIJ.