Simulation of Nonmetallic Inclusions in a Continuous Casting Strand

Merder

Archives of Metallurgy and Materials

2015

The liquid steel flow structure in the tundish has a very substantial effect on the quality of the final product and on efficient casting conditions. Numerous model studies are being carried out to explain the effect of the tundish working conditions on casting processes.It is necessary to analyze the structure of liquid steel flow, which is strongly supported with numerical modeling. In numerical modeling, a choice of a proper turbulence model is crucial as it has a great impact on the flow structure of the fluid in the analyzed test facility. So far most numerical simulations has been done using RANS method (Reynolds-averaged Navier-Stokes equations) but in that case one get information about the averaged values of the turbulent flow. In presented study, numerical simulations using large eddy simulations (LES) method were used and compared to RANS results. In both cases, numerical simulations are carried out with the finite-volume commercial code AnsysFluent.Keywords: tundish, continuous casting, numerical modeling Struktura przepływu ciekłej stali w kadzi pośredniej ma bardzo istotny wpływ na warunki odlewania, a tym samym na jakość wyrobu końcowego. W celu określenia struktury przepływu w kadzi oraz analizy jej wpływu na warunki pracy urządzenia do ciągłego odlewania stali (COS) prowadzone są liczne badania modelowe: fizykalne i numeryczne.W modelowaniu numerycznym, wybór odpowiedniego modelu turbulencji jest kluczowy, ponieważ ma ogromny wpływ na strukturę przepływu płynu w analizowanym obiekcie badawczym. Do tej pory, największą ilość symulacji numerycznych przeprowadzono z wykorzystaniem metody RANS (Reynolds-averaged Navier-Stokes equations). W przypadku tej metody dostajemy jednak jedynie informacje o uśrednionych wartościach przepływu turbulentnego, z jakim mamy do czynienia w kadziach pośrednich. W prezentowanej pracy natomiast, przedstawiono wyniki symulacji numerycznych przeprowadzonych z wykorzystaniem metody wielkich wirów (Large Eddy Simulation, LES) i porównano je z wynikami RANS. W obu przypadkach, symulacje numeryczne zostały przeprowadzone z wykorzystaniem komercyjnego kodu AnsysFluent.

Section: Introductionmentioning

confidence: 99%

Investigation of the Flow Structure in the Tundish with the Use of Rans and Les Methods

Merder

Archives of Metallurgy and Materials

2015

“…For Eulerian approach, 1,9,10) the governing equation for inclusion transport, which is written in the general form of Eq. (1), can be solved by the finite volume method.…”

Section: Introductionmentioning

confidence: 99%

Mathematical Model for Cluster-Inclusion’s Collision-Growth in Inclusion Cloud at Continuous Casting Mold

Lei¹,

Zhao

Geng³

2014

ISIJ Int.

The inclusion's morphology and size play a strong role in the steel product quality, so it is very important to have a deep insight into the inclusion's collision-growth in the continuous caster. In order to describe the formation of the cluster-inclusion, a mathematical model and the related source code are developed to trace the inclusion's movement and collision-growth in the inclusion cloud. Such a model includes two sub-models. Firstly, the spatial distribution of turbulent flow and the inclusion's number density and the characteristic radius after Stokes collision and turbulent collision are obtained by Eulerian approach. Secondly, the inclusion's trajectory and the related inclusion fractal growth are predicted by Lagrangian approach. Numerical results show that the spatial distributions of the inclusion volumetric concentration, number density and characteristic radius have some features of the upper and lower recirculation zone due to the fluid flow. For an inclusion particle, the bigger inclusion has more chances to catch other inclusions and forms a more complex cluster-structure. Among the forces acting on the inclusion, the pressure gradient force, Basset history force, the visual mass force, the gravitational force and the buoyancy force should be considered in order to describe the inclusion's exact motion. Furthermore, the pressure gradient force, the Basset force, the visual mass force follow the same variation rule along with the inclusion's trajectory.

“…3,4) Inclusion behavior in the continuous caster is a particularly challenging task because it frequently requires the investigator to deal with the collisioncoalescence among inclusions. Trajectory model 3,5) and inclusion mass conservation model 6,7) are employed to investigate inclusion behavior in the continuous casting mold, but it can not consider the collision among inclusions. Inclusion mass-population conservation model 8,9) and inclusion fractal-growth model 10) can treat with the collisioncoalescence in the liquid zone of the mold successfully.…”

Section: Introductionmentioning

confidence: 99%

A Continuum Model of Solidification and Inclusion Collision-growth in the Slab Continuous Casting Caster

Lei¹,

Geng²,

He³

2009

ISIJ Int.

A coupled mathematical model on fluid flow, heat and solute transport, and inclusion transport is developed to investigate turbulent flow, solidification, and inclusion collision-growth in the slab continuous caster. The behaviors of inclusion and solute in the steel belong to mass transfer phenomena, but inclusion transport is different from solute transfer in the liquid phase zone, mush zone and solid phase zone. In the continuous caster, turbulent collision and Stokes collision, which are the major factor causing inclusions to coalescence, have been taken into account in the mathematical model. All these differential equations have the same basic structure and can be solved by the same numerical method. Influenced by the fluid flow, the temperature, carbon element and inclusion in the molten steel have similar spatial distribution as the fluid flow in the continuous caster. Their spatial distribution can be divided into the upper and lower recirculation zones, but their distributions have their own characteristics. Near the center of the recirculation zones, the temperature of molten steel and the characteristic inclusion concentration and the characteristic inclusion number density are lower, but the carbon concentration and the inclusion size are greater. Due to the interaction between the movement of solidified shell and the downward flow, a small corner-vortex appears near the meniscus. The initial solidified shell forms near the meniscus, so there is a few of indigenous inclusions with small size in the initial solidified shell.