Mathematical Modeling of Inclusions Deposition at the Upper Tundish Nozzle and the Submerged Entry Nozzle

摘要

Nozzle clogging is still a concern for steel makers due to the high-quality requirements and productivity in the continuous casting. The present work studies the factors involved in the inclusion deposition at the nozzle wall using numerical and analytical techniques. For this, a detailed fluid dynamic analysis inside the nozzle in a coupled tundish-mold system is undertaken. The results show that the inclusions reaching the nozzle, only 30% get deposited along its walls mainly at the upper tundish nozzle (UTN) and at the submerged entry nozzle (SEN) ports. These areas of higher deposition are identified close to a low static pressure and a high turbulent kinetic energy dissipation zones. The high-energy dissipation induces a fluctuant velocity increment; consequently, the mean flow velocity increases forcing a reduction of the static pressure in order to preserve the mechanical energy balance. This mechanical energy imbalance is identified as mechanical energy dissipation being recognized by an increment in the vorticity and quantified by an additional term into Bernoulli equation. This complex phenomenon induces zones of high turbulent flow from which the inclusions tend to move toward lower turbulence regions, explaining why the inclusions get deposited in these two typical zones promoting the deleterious clogging phenomenon.