Analysis of heat transfer and fluid flow in the continuous casting mold with electromagnetic brake.

Takatani, Kouji; Nakai, Ken; Kasai, Norifumi; Watanabe, Tadao; Nakajima, Hidemasa

doi:10.2355/isijinternational.29.1063

Cited by 45 publications

(36 citation statements)

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“…Thus, the correlation between flow pattern and solidified shell in the CC process has not been clearly established. [3][4][5][6] Although a minority of study 7,8) considered the solidification phenomena, the effects of EMBr on the temperature field and solidified shell in CC process were not shown in those works. Therefore, it may be meaningful that the investigation of the controled flow pattern by EMBr and solidification is performed.…”

Section: Introductionmentioning

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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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: Introductionmentioning

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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“…Statically-applied electromagnetic-field (EMF) configurations include local [circular fields on each side of the Submerged Entry Nozzle (SEN)], [1][2][3][4][5] single-ruler (a rectangular field across the entire mold width), [5,6] and double-ruler [6][7][8][9] (two rulershaped fields, with one positioned across the mold near the meniscus and the other one aligned through or below the nozzle ports). When the EMF coil currents are adjusted to produce equal peak field strengths, this double-ruler configuration is commercially known as ''Flow-Control-Mold'' or ''FC-Mold'' ElectroMagnetic Braking or ''EMBr.''…”

Section: Introductionmentioning

confidence: 99%

“…The regions of the strongest magnetic fields tend to deflect the flowing steel, altering the time-averaged flow, which has been the subject of many previous modeling studies. [1,3,4,6,[10][11][12][13] The effect on transient flow has received less attention in the studies so far.…”

Section: Introductionmentioning

confidence: 99%

Large Eddy Simulations of Double-Ruler Electromagnetic Field Effect on Transient Flow During Continuous Casting

Singh

Thomas

Vanka

2014

Metall Mater Trans B

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Transient flow during nominally steady conditions is responsible for many intermittent defects during the continuous casting of steel. The double-ruler electromagnetic field configuration, or ''FC-Mold EMBr,'' is popular in commercial slab casting as it provides independent control of the applied static field near the jet and free surface regions of the mold. In the current study, transient flow in a typical commercial caster is simulated in the absence and in the presence of a double-ruler magnetic field, with rulers of equal strengths. Large eddy simulations with the inhouse code CU-FLOW resolve the important transient behavior, using grids of over five million cells with a fast parallel solver. In the absence of a magnetic field, a double-roll pattern is observed, with transient unbalanced behavior, high surface velocities (~0.5 m/s), surface vortex formation, and very large surface-level fluctuations (~±12 mm). Applying the magnetic field suppresses the unbalanced behavior, producing a more complex mold flow pattern, but with much lower surface velocities (~0.1 m/s), and a flat surface level with small level fluctuations (<±1 mm). Nail board measurements taken at this commercial caster, in the absence of the field, matched reasonably well with the calculated results, both quantitatively and qualitatively.

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“…[1][2][3][4][5][6][7][8][9][10][11] For example, Cukierski and Thomas reported that local EMBr usually decreases the surface velocity, depending on the submergence depth of the Submerged Entry Nozzle (SEN). 8) Wang and Zhang investigated the effects of local EMBr on the fluid flow, heat transfer, and transport of argon bubbles and inclusions in the mold.…”

Section: Introductionmentioning

confidence: 99%

Transient Fluid Flow during Steady Continuous Casting of Steel Slabs: Part II. Effect of Double-Ruler Electro-Magnetic Braking

2014

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Plant measurements and computational models of transient flow with and without electromagnetic fields are applied to investigate transient phenomena in the nozzle and mold region during nominallysteady steel slab casting. In Part II of this two-part article, the effect of applying a static magnetic field on stabilizing the transient flow is investigated by modeling a double-ruler Electro-Magnetic Braking (EMBr) system, under conditions where measurements were obtained. A Reynolds Averaged Navier-Stokes (RANS) computational model using the standard k-ε model is employed with a magnetic field distribution extrapolated from measurements. The magnetic field decreases velocity fluctuations and deflects the jet flow downward in the mold, resulting in a flatter surface level and slower surface flow with slightly better stability. The effect of EMBr on surface level and surface velocity, including the effect of the real conducting steel shell, falls between the cases assuming perfectly-conducting and insulating walls. Measurements using an eddy current sensor and nail boards were performed to quantify the effect of EMBr on level and velocity at the mold surface. Power spectrum analysis of the surface level variations measured by the sensor revealed a frequency peak at ~0.03 Hz (~35 seconds) both with and without the EMBr. With EMBr, the surface level is more stable, with lower amplitude fluctuations, and higher frequency sloshing. The EMBr also produced ~20% lower surface velocity, with ~60% less velocity variations. Finally, the motion of the slag-steel interface level causes mainly lifting rather than displacement of the molten slag layer, especially near the SEN.

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Analysis of heat transfer and fluid flow in the continuous casting mold with electromagnetic brake.

Cited by 45 publications

References 0 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.

Large Eddy Simulations of Double-Ruler Electromagnetic Field Effect on Transient Flow During Continuous Casting

Transient Fluid Flow during Steady Continuous Casting of Steel Slabs: Part II. Effect of Double-Ruler Electro-Magnetic Braking

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