A three-dimensional simulation of coupled turbulent flow and macroscopic solidification heat transfer for continuous slab casters

Seyedein, S.H.; Hasan, Mainul

doi:10.1016/s0017-9310(97)00064-1

Cited by 84 publications

(58 citation statements)

References 14 publications

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“…Thus, it is very difficult to employ the wall functions. In this study, a revised version of low-Reynolds number k-e turbulence model by Launder and Sharma, 15) adopted by a few previous studies, 13,14) is used to consider the turbulent characteristics. A treatment for the release of latent heat in a mushy zone depends on a single-domain-based enthalpy method.…”

Section: Mathematical Modelmentioning

confidence: 99%

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Numerical Simulation of the Coupled Turbulent Flow and Macroscopic Solidification in Continuous Casting with Electromagnetic Brake.

Kim

Cho

2000

ISIJ International

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A computer program has been developed for analyzing the three-dimensional, steady conservation equations for transport phenomena in a slab continuous casting process with Electromagnetic Brake (EMBr) to investigate the effect of EMBr on the turbulent melt-flow, temperature fields, and macroscopic solidification of the molten metal. The enthalpy-porosity relation was employed to suppress the velocity within a mushy region. A revised low-Reynolds number k-e turbulence model was used to consider the turbulent effects. The electromagnetic field was described by Maxwell equations. The application of EMBr to the mold region results in the decrease of the transfer of superheat to the narrow face, the increase of temperature in freesurface region and most part of the melt of submold region, and the higher temperature gradients near the solidifying shell. The increasing magnetic flux density has effect mainly on the surface temperature of the solidifying shell at the narrow face, hardly on that at the wide face. It is seen that in the presence of EMBr, a thicker solidifying shell is obtained at the narrow face of slab.KEY WORDS: numerical simulation; turbulent flow; macroscopic solidification; electromagnetic brake (EMBr); continuous casting (CC) process.In the present study, a three-dimensional analysis of the coupled turbulent flow, solidification, and induced electric field in a slab CC process with EMBr system, is performed using a developed computer program. And based on the corresponding results, the velocity and temperature distributions are investigated. The suppression effects of velocity in phase-change zone are considered depending on a porosity-enthalpy relationship. The turbulent characteristics of melt-flow in the liquid region are taken into account using a revised version of low-Reynolds number k-e turbulence model by Launder and Sharma. 15) TheoryIn a commercial continuous caster, the melt is fed through a submerged nozzle from tundish into a vibrating, water-cooled mold. The jet-flow of melt is suppressed by an electromagnetic force due to the EMBr system applied to the mold. The melt from which sufficient heat is extracted by the mold, forms a solidified shell, and moves down into secondary cooling zones by water spray. This study is interested in the vertical part only of the continuous caster, composed of the vertical and curved parts. A schematic diagram of slab caster with EMBr system is shown in Fig. 1(a). The computational domain shown in Fig. 1(b) is chosen based on the symmetry of caster shape displayed in Fig. 1(a). A circular shape of nozzle is assumed to be the rectangular cross-sectional flow-area with an equivalent hydraulic diameter. Mathematical ModelIn a commercial scale of CC process, the melt-flow fed into the caster through a bifurcated SEN has the characteristics of turbulent flow. Standard k-e model of turbulence is especially applicable to the flow regions with high turbulent Reynolds number Re t ϭrk 2 /me and cannot be applied near the solid walls, where the viscous effects bec...

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Section: Mathematical Modelmentioning

confidence: 99%

“…13,14) The value of d is of the order of 1ϫ10 Ϫ4 m. The constant D 0 is assumed to be 1.8ϫ10 10 in this study. The constant q, introduced to avoid the division by zero, is set at 0.001.…”

Section: Mathematical Modelmentioning

confidence: 99%

Numerical Simulation of the Coupled Turbulent Flow and Macroscopic Solidification in Continuous Casting with Electromagnetic Brake.

Kim

Cho

2000

ISIJ International

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“…[1][2][3][4][5][6][7][8][9][10] Fewer publications related with fluid flow in billet molds and particle image velocimetry (PIV) measurements are available, [11][12][13][14][15] probably because the conventional straight nozzles employed in this field work in a much more confined space, inducing what would be called standard flows with small variations of fluid flow patterns. However, the study presented here made clear that the complex nature of turbulent flows prevails even under the conditions of very stable flows, such as those expected in billet molds.…”

Section: Introductionmentioning

confidence: 99%

Influence of Straight Nozzles on Fluid Flow in Mold and Billet Quality

Torres-Alonso

Morales

Garcia-Hernandez

et al. 2008

Metall Mater Trans B

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Flux entrainment defects in a billet mold with two straight nozzles (outer radius of 60 mm, S60, and 73 mm, S73, and same interior radius of 36 mm) are studied using mathematical simulations and experimental techniques including particle image velocimetry (PIV), tracer injection, and water-oil modeling. Experimental findings indicated that using either of these nozzles at the deepest position of 135 mm (measured from the nozzle tip to the meniscus level) induces a flow near the meniscus, characterized by low turbulence yielding very stable water-oil interfaces. Simultaneously, owing to the mold radius, the entry jet induces a nonsymmetric flow downstream in the mold. At the shallow position of 90 mm, nozzle S73 induces a flow characterized by cyclic velocity spikes of low frequency and short duration close to the meniscus making the metal-flux interface highly instable. As the gap between the nozzle outer wall and the mold face is narrower and the nozzle position is shallower, the fluid close to the meniscus develops zones of high vorticity gradients leading to rotating flows, which are responsible for that instability. Water-oil experiments indicated that during the generation of this phenomenon, water flow entrains oil droplets in the side of the mold inner radius. Instability of metal-flux interface is then a consequence of the fluctuating nature of the recirculating flows in the mold, which induce upper rotating flows with large vorticity gradients. This mechanism explains actual flux entrainment defects in a billet caster.

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“…In the present work, the well-known enthalpy-porosity based method was implemented (Voller and Prakash, 1997;Seyedein and Hasan, 1997;Begum, 2013;Begum and Hasan,2014). The Darcy law for porous media was used to predict the flow of the molten metal in the mushy region (Vafai et al, 1985).…”

Section: Governing Equations For Laminar/turbulent Melt Velocity and mentioning

confidence: 99%

Solidification Characteristics of Brass in a Direct Chill Caster

Hasan¹,

Begum²

2016

AJHMT

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In this study, an industrial-sized slab for a standard brass alloy has been numerically simulated in a vertical and conventional direct chill caster using an in-house 3-D CFD code. The studied caster consists of a hot-top mold which is fitted with a porous filter across the entire cross-section within the hot-top. The BrinkmannForchimier-Extended non-Darcy model for turbulent flow is used to macroscopically model the melt flow through the porous filter. The velocity, and temperature profiles and quantitative values for shell thickness at the exit of the mold, sump depth and mushy thickness are provided for four casting speeds varying from 40 to 100 mm/min. The shell thickness at the exit of the mold is also presented for various metal-mold contact lengths, convective heat transfer coefficients at the metal-mold contact region and Darcy numbers of the porous filter. Important correlations are provided for the aforementioned quantities with casting speed to facilitate the design of such a caster.

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A three-dimensional simulation of coupled turbulent flow and macroscopic solidification heat transfer for continuous slab casters

Cited by 84 publications

References 14 publications

Numerical Simulation of the Coupled Turbulent Flow and Macroscopic Solidification in Continuous Casting with Electromagnetic Brake.

Numerical Simulation of the Coupled Turbulent Flow and Macroscopic Solidification in Continuous Casting with Electromagnetic Brake.

Influence of Straight Nozzles on Fluid Flow in Mold and Billet Quality

Solidification Characteristics of Brass in a Direct Chill Caster

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