The fluid flow of liquid steel in a wide slab mold (1880 9 230 mm) influenced by two different submerged entry nozzle (SEN) designs (bifurcated nozzles with rectangular, SEN-R, vs square, SEN-S, ports) and immersion depths of 115 and 185 mm was studied using a 1:1 scale water model. To analyze the fluid dynamics, particle image velocimetry and video recording techniques were used. The fluid-flow dynamics indicate that the discharging jets using either SEN design suffer strong wandering and raveling effects that enhance turbulence in the meniscus region. The preceding results show the existence of velocity spikes (defined as velocities with magnitudes that exceed the standard deviation of the average velocity) in the submeniscus region. Using the SEN-R ports yields more velocity spikes per minute with larger magnitudes than using the SEN-S, which could be the main cause of the detrimental quality of steel. The capability of slag entrainment by the flow developed by a nozzle was the criterion employed to evaluate quantitatively the merits of one nozzle over the other. This criterion is based on the capillary number, which gives the ratio between viscous-inertial and surface forces at the metalslag interface.

Flow patterns of liquid steel in a thick slab mold, fed by bifurcated nozzles, are modeled through water modeling using characterization techniques such as particle image velocimetry (PIV), ultrasound velocimetry probe (UPV), and mathematical simulations using the large eddy simulation (LES) model. Geometries of nozzle ports include circular and square shapes with similar cross‐section area. Square ports deliver wandering jets that occupy about 66% of the port area, and are raveled during their pass through the mold impacting the narrow face. Circular ports deliver compact jets mainly through the lower edge occupying only about 45% of the port area. The analysis of the flow structures indicates that the circular ports form more turbulent jets than square ones for the same flow rate of liquid. Mathematical simulations, using the LES model, predict acceptably well measured velocity fields. Slag entrainment through mechanisms of shear‐drag forces at the metal–slag interface is estimated through a critical capillary number which involves slag viscosity, interfacial tension, and fluid velocity. At deep nozzle immersions, this capillary model predicts more slag entrainment using the bifurcated nozzle with circular ports.

The aim research work is to study a new ladle shroud concept and design to assist in the reduction of slag emulsification in the tundish during ladle change-over operations. For this, a tundish analogue water model is designed and constructed based on Froude similarity criterion; a deeper analysis of the flow behavior is undertaken by mathematical simulation. Tap water and silicon oil are employed to simulate molten steel and slag. The modeling results show that using a conventional ladle shroud, the water is delivered with an excessive amount of turbulent kinetic energy which is dissipated inside the tundish bath, generating strong mixing flow patterns and entrapping a massive amount of oil. Furthermore, during this transient operation the conventional shroud induces oil dragging into the bath at zones next to the entry volume, producing continuous oil emulsification. In contrast, the proposed ladle shroud dissipates the turbulent kinetic energy before the water enters the tundish model, promoting less intense mixing patterns. Also, the dragging zone disappears; thus, the amount of oil emulsification is reduced significantly. Consequently, if the turbulent kinetic energy is dissipated before the steel enters the tundish, it will be possible to reduce the slag emulsification and the slag opening area.[ Ã ] Prof.

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