Mathematical Modeling of Liquid Slag Layer Fluctuation and Slag Droplets Entrainment in a Continuous Casting Mold Based on VOF-LES Method

2017 ◽  
Vol 36 (5) ◽  
pp. 551-565 ◽  
Author(s):  
Peng Zhao ◽  
Qiang Li ◽  
Shi Bo Kuang ◽  
Zongshu Zou
Keyword(s):  
Continuous Casting ◽  
Casting Speed ◽  
Transient Flow ◽  
Slag Layer ◽  
Surface Flow ◽  
Scale Model ◽  
Continuous Casting Mold ◽  
Casting Mold ◽  
Slag Entrainment ◽  
The Asymmetry

AbstractThe slag behaviors, directly relating with the qualities of the final cast products, are influenced by the transient surface flow of liquid steel in a continuous casting mold. A one-half scale model is used to investigate the slag behaviors and their droplets entrainment. The model based on Volume of Fluid (VOF) multiphase coupled with Large Eddy Simulation (LES) is established to further illuminate the phenomena of the liquid oil layer fluctuation, the slag “eye” regions, and the slag entrainment observed in water experiment. The effects of casting speeds on the slag behaviors and their entrained droplets are investigated. The results show that the fluctuation of the oil layer is influenced by the transient flow. The calculations for the oil layer profile, the accumulation, and protrusions of oil layer are consistent with the water experiment. The asymmetry of the slag “eye” regions is also influenced by the asymmetry of free surface and transient turbulent flow. The “eye” regions near the narrow wall show distinct asymmetric change at different casting speeds. At a lower casting speed, the slag “eye” regions change irregularly and display the alternate process of open and collapse at the two sides of the narrow walls of the model. While at a relative higher casting speed, the slag layer gathers toward the nozzle, and the slag “eye” regions gradually grow and always open. The simulation model can reveal that the mechanism of the slag entrainment includes two main modes: the cutting or dragging mode and shear layer instability. The average diameter and amount of the entrained droplets are calculated through the UDF codes of ANSYS FLUENT software, and the size distribution of the entrained droplets is also counted. When the casting speed is lower, the dominant diameters of the entrained droplets range between 2 and 3 mm. With casting speed increase, the distribution of the droplets becomes wider, and there is a gradually increase in the percentage of larger droplets with a size of 4–6 mm.

scholarly journals Analysis of the Depth of Immersion of the Submerged Entry Nozzle on the Oscillations of the Meniscus in a Continuous Casting Mold

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 596 ◽  
Author(s):  
F. Saldaña-Salas ◽  
E. Torres-Alonso ◽  
J.A. Ramos-Banderas ◽  
G. Solorio-Díaz ◽  
C.A. Hernández-Bocanegra
Keyword(s):  
Continuous Casting ◽  
Fluid Dynamic ◽  
Submerged Entry Nozzle ◽  
Dynamic Structure ◽  
Slag Layer ◽  
Three Dimensions ◽  
Scale Model ◽  
Continuous Casting Mold ◽  
Casting Mold ◽  
High Elevations

In this study the effects of the depth of immersion of the Submerged Entry Nozzles (SEN) on the fluid-dynamic structure, oscillations of the free surface and opening of the slag layer, in a continuous casting mold for conventional slab of steel were analyzed. For this work, a water/oil/air system was used in a 1:1 scale model, using the techniques of Particle Image Velocimetry (PIV), colorimetry and mathematical multiphase simulation. The results of the fluid dynamics by PIV agree with those obtained in the mathematical simulation, as well as with the dispersion of dye. It was observed that working with immersion depths of 100 mm or less could be detrimental to steel quality because they promote surface oscillations of a higher degree of Stokes with high elevations and asymmetry in their three dimensions. In addition, this generates an excessive opening of the oil layer which was corroborated through the quantification of the F index. On the other hand, with depths of immersion in the range of 150–200 mm, lower oscillations were obtained as well as zones of low speed near the wall of the SEN and a smaller opening of the oil layer.

scholarly journals Measurement of Molten Steel Velocity near the Surface and Modeling for Transient Fluid Flow in the Continuous Casting Mold

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 36 ◽  
Author(s):  
Tao Zhang ◽  
Jian Yang ◽  
Peng Jiang
Keyword(s):  
Continuous Casting ◽  
Molten Steel ◽  
Casting Speed ◽  
Surface Defects ◽  
Transient Flow ◽  
Flow Behavior ◽  
Surface Velocity ◽  
Phase Method ◽  
Mold Surface ◽  
Continuous Casting Mold

In the current work, a rod deflection method (RDM) is conducted to measure the velocity of molten steel near the surface in continuous casting (CC) mold. With the experimental measurement, the flow velocity and direction of molten steel can be obtained. In addition, a mathematical model combining the computational fluid dynamics (CFD) and discrete phase method (DPM) has been developed to calculate the transient flow field in a CC mold. The simulation results are compared and validated with the plant measurement results. Reasonable agreements between the measured and simulated results are obtained, both in the trends and magnitudes for the flow velocities of molten steel near the mold surface. Based on the measured and calculated results, the velocity of molten steel near the surface in the mold increases with increasing casting speed and the casting speed can change the flow pattern in the mold. Furthermore, three different types of flow patterns of molten steel in the mold can be obtained. The pattern A is the single-roll-flow (SRF) and the pattern C is the double-roll-flow (DRF). The pattern B is a transition state between DRF and SRF, which is neither cause the vortices nor excessive surface velocity on the meniscus, so the slag entrainment rarely occurs. Argon gas injection can slow down the molten steel velocity and uplift the jet zone, due to the buoyancy of bubbles. Combination of the measurement and numerical simulation is an effective tool to investigate the transient flow behavior in the CC mold and optimize the actual operation parameters of continuous casting to avoid the surface defects of the automobile outer panels.

scholarly journals Measurement of Surface Velocity in a 150 mm × 1270 mm Slab Continuous-Casting Mold

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 428
Author(s):  
Yang Wang ◽  
Jie Feng ◽  
Shufeng Yang ◽  
Jingshe Li
Keyword(s):  
Continuous Casting ◽  
Particle Image ◽  
Slag Layer ◽  
Surface Velocity ◽  
Continuous Casting Mold ◽  
Casting Mold ◽  
Slab Continuous Casting ◽  
Image Velocimetry ◽  
Nail Diameter

Surface velocity in the continuous-casting mold needs to be studied to better control the quality of steel products. In this paper, the measurement of surface velocity in a 150 mm × 1270 mm slab continuous-casting mold was investigated. Taking the slag layer into consideration, a numerical simulation was performed which was validated by a particle image velocimetry test. A nail-board experiment was also conducted to measure surface velocity in the continuous-casting mold. The effect of nail diameter used in nail-board experiment on the measurement of the surface velocity was also discussed to improve the precision of nail-board experiment result. The results showed that the maximum surface velocity was 0.739 m/s around the mid-section of the free surface, and the results of nail-board experiments were more accurate when the steel nail diameter was 10 mm.

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