Numerical analysis of fluid flow in continuous casting mold by bubble dispersion model.

Bessho, Nagayasu; Yoda, Ryoji; Yamasaki, Hiroyuki; Fujii, Tetsuya; Nozaki, Tsutomu; Takatori, Seiji

doi:10.2355/isijinternational.31.40

Cited by 35 publications

(29 citation statements)

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“…166) cles than straight (vertical) mold casters, 168) because the particles gradually move upwards towards the inside radius while they spiral with the liquid in the lower recirculation zone. Most particles are captured 1-3 m below the meniscus, independent of casting speed, 162,169) which corresponds to a specific distance through the strand thickness. 163) Often, inclusions concentrate at one-eighth to one-quarter of the thickness from the top of the inside radius surface, 112,140) in addition to the surfaces, as verified by AK Steel Middletown Works (Fig.…”

Section: Caster Curvaturementioning

confidence: 99%

State of the Art in Evaluation and Control of Steel Cleanliness.

2003

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This paper first reviews the current "state-of-the-art" in the evaluation of steel cleanliness, discussing over 20 different methods. The demand for cleaner steels requires lowering non-metallic oxide inclusions and also controlling their morphology, composition and size distribution. Because no single method can measure all of these aspects accurately, it is best to combine several methods together to quantify steel cleanliness in a given operation. Owing to the cost, time requirements, and sampling difficulties, steel cleanliness is widely inferred using total oxygen, nitrogen pick-up, and other indirect methods. Recent cleanliness values using these indicators are summarized for LCAK at many steel plants around the world. Secondly, this paper reviews operating practices to improve steel cleanliness at the ladle, tundish and continuous caster, emphasizing findings quantified with plant measurements. Inclusions come from many sources, including deoxidation, reoxidation, slag entrapment, refractory wear, and chemical reactions. They generate many defects such as cracks and slivers in the steel product. Steel cleanliness is controlled by attention to a wide range of important operating conditions throughout the steelmaking and casting processes. For ladle operations, FeO and MnO in the slag, ladle treatments, and inclusion modification are discussed. For tundish operations, tundish depth and capacity, casting transitions, refractory lining, tundish flux; gas stirring, and flow controls are discussed. Important transfer operations from ladle to tundish and from tundish to mold, such as argon protection, sealing issues, and SEN clogging are summarized. Caster operations reviewed include the effect of casting speed, fluid flow pattern control, surface level control, and caster curvature.

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Section: Caster Curvaturementioning

confidence: 99%

State of the Art in Evaluation and Control of Steel Cleanliness.

2003

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“…Several methods have been employed to measure the fluid flow velocity vectors in continuous casting mold system, including LDV (Laser Doppler Velocimetry) for mold 16,57) and for SEN nozzle 58,59) ), PIV (Particle Image Velocimetry), 19,25,60,61) hot wire anemometry 62) ; and propeller flow meters. [63][64][65] Figure 3 compares the instantaneous flow patterns predicted using physical and mathematical models for a typical double-roll flow pattern condition. 19) In this particular flow pattern, the steel jets first impinge on the narrow faces before turning upward towards the top surface and back across towards the SEN. Changing casting conditions (e.g.…”

Section: Flow In the Moldmentioning

confidence: 99%

Mathematical Modeling of Iron and Steel Making Processes. Mathematical Modeling of Fluid Flow in Continuous Casting.

2001

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Fluid flow is very important to quality in the continuous casting of steel. With the high cost of empirical investigation and the increasing power of computer hardware and software, mathematical modeling is becoming an important tool to understand fluid flow phenomena. This paper reviews recent developments in modeling phenomena related to fluid flow in the continuous casting mold region, and the resulting implications for improving the process. These phenomena include turbulent flow in the nozzle and mold, the transport of bubbles and inclusion particles, multi-phase flow phenomena, the effect of electromagnetic forces, heat transfer, interfacial phenomena and interactions between the steel surface and the slag layers, the transport of solute elements and segregation. The work summarized in this paper can help to provide direction for further modeling investigation of the continuous casting mold, and to improve understanding of this important process.KEY WORDS: mathematical modeling; computational simulation; review; continuous casting; nozzles; molds; multiphase; turbulent; fluid flow; electromagnetic; coupled solidification; inclusion entrapment; segregation.steel. This paper will review recent developments in modeling each of the phenomena above, which are related to fluid flow in the continuous casting mold, and the resulting implications for improving the continuous casting process. Fluid Flow ModelingA typical three dimensional fluid flow model solves the continuity equation and Navier Stokes equations for incompressible Newtonian fluids, which are based on conserving mass (one equation) and momentum (three equations) at every point in a computational domain. 17,18) The solution of these equations, given elsewhere in this issue, 19) yields the pressure and velocity components at every point in the domain. At the high flow rates involved in this process, these models must incorporate turbulent fluid flow. Many different turbulence models have been employed by different researchers for fluid flow in continuous casting, such as effective viscosity models 20,21) (for the cylindrical mold and straight nozzle), one equation turbulence models (turbulent energy plus a given length-scale), 22) two-equation turbulence models such as the K-e Model, 19,23) LES (Large Eddy Simulation), [24][25][26][27][28] possibly with a SGS (sub-grid scale) model, 29,30) and DNS (Direction Numerical Simulation). 19)Among these models, direct numerical simulation is the simplest yet most computationally-demanding method. DNS uses a fine enough grid (mesh), to capture all of the turbulent eddies and their motion with time. To achieve more computationally-efficient results, turbulence is usually modeled on a courser grid using a time-averaged approximation, such as the popular K-e model, 23) which averages out the effect of turbulence using an increased effective viscosity field, m eff . This approach requires solving two additional partial differential equations for the transport of turbulent kinetic energy and its dissipation rate.19...

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“…Various designs of submerged entry nozzle are also proposed to optimize spouting stream from nozzle. [7][8][9] Those results are generally based on experimental study with water model and/or numerical simulation of fluid dynamics. [7][8][9] Although fluid flow in the nozzle significantly effects on spouting stream as a source of mold flow, few studies have been done in this field.…”

Section: Introductionmentioning

confidence: 99%

“…[7][8][9] Those results are generally based on experimental study with water model and/or numerical simulation of fluid dynamics. [7][8][9] Although fluid flow in the nozzle significantly effects on spouting stream as a source of mold flow, few studies have been done in this field. 10,11) Uneven flow velocity depending on plate sliding direction was clarified, 11) however, precise consideration of gas-liquid multi-phase-flow in numerical simulations and replication of steel flow by water models are insufficient to reveal fluid flow in submerged entry nozzle.…”

Section: Introductionmentioning

confidence: 99%

“…It is essential to stabilize fluid flow in the mold to produce high quality steel, therefore, much research has been performed controlling flow pattern of the molten steel from various technical aspects. [1][2][3][4][5][6][7][8][9] Application of electromagnetic force into molten steel flow in the mold and optimizing submerged entry nozzle design is a possible effective measure. Various types of static magnetic field (brake) 3,4) and traveling magnetic field 5,6) are installed into commercial continuous caster.…”

Section: Introductionmentioning

confidence: 99%

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