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

Torres-Alonso, E.; Morales, R. D.; Garcia-Hernandez, Saul; Nájera-Bastida, Alfonso; Sandoval-Ramos, A.

doi:10.1007/s11663-008-9202-2

Cited by 26 publications

(30 citation statements)

References 16 publications

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“…Using the straight SEN, the level fluctuation is less than 1 mm and the velocity magnitude is far from a reasonable interval. One of the reasons for the weak and calm top free surface characteristics is that the use of two nozzles per mold for uniform steel feeding which can reduce the impact caused by molten steel injection, and meanwhile a few publications 9,21) have suggested that the flow near the meniscus is characterized by a low turbulence.…”

Section: Top Free Surface Characteristicsmentioning

confidence: 99%

Transport Phenomena in a Beam-Blank Continuous Casting Mold with Two Types of Submerged Entry Nozzle

Zhu

2015

ISIJ Int.

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A three-dimensional full-coupled mathematical model is established to study the fluid flow, heat transfer and solidification in a 450 mm × 350 mm × 90 mm beam-blank mold with two different types of submerged entry nozzle (SEN), namely single-port straight SEN and three-port radial flow SEN. Water modeling experiments, industrial trials and public results available in literature are performed to validate the numerical results. The results show that, with the straight SEN which has been widely applied in beam-blank continuous casting, there is a very inactive top free surface in the mold which level fluctuation magnitude is less than 1 mm and velocity magnitude is far from a reasonable interval, and the shell thickness distribution at the mold exit is very uneven, thick at the web but thin at the fillet. Moreover, there exists a "wavy contour" at the flange due to the washing effect of the off-center molten steel jet. While with the new designed radial flow SEN, a suitable meniscus status and a more uniform shell thickness at the mold exit can be obtained, which is helpful to avoid the breakouts caused by the rupture of thin fillet and the flange depression. The "self-braking" effect caused by two radial flow SENs provides good flow stability at the web center.

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Section: Top Free Surface Characteristicsmentioning

confidence: 99%

Transport Phenomena in a Beam-Blank Continuous Casting Mold with Two Types of Submerged Entry Nozzle

Zhu

2015

ISIJ Int.

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“…3(d)) where there is an ascending flow to the bath top in the side of the inner mould radius that coincides with results previously presented in a water model. 24) A feasible explanation for the braking effects of both cases is the existence of large buoyancy forces induced by the temperature gradients and the downwards shearing stresses produced by the pulling speed or casting speed of the shell. This later effect is particularly effective along the mould walls as can be seen in Figs.…”

Section: Model Descriptionmentioning

confidence: 99%

“…Generally speaking these changes lead to stronger stirring conditions of the melt at meniscus level. Using a water model and PIV measurements, Torres-Alonso et al 24) found that this narrower gap and the step of the lower ring of nozzle S-73 (see Fig. 1(e)), work synergistically to induce a channelling flow which alters the flow significantly.…”

Section: Model Descriptionmentioning

confidence: 99%

“…This later factor is of extreme importance since, as the authors have demonstrated, steel flows dynamics in billet moulds are actually very complex and interact closely with mould flux. 24) The objectives and aims of the present work consist of the development of a mathematical model for steel solidification which includes the effects of nozzle design influencing, fluid flow patterns, mould powder chemistry and heat transfer. This model is applied to simulate shell growth dynamics and shell thinning effects affected by casting variables.…”

Section: Introductionmentioning

confidence: 99%

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Shell Thinning Phenomena Affected by Heat Transfer, Nozzle Design and Flux Chemistry in Billets Moulds

Nájera-Bastida¹,

Morales²,

Garcia-Hernandez³

et al. 2010

ISIJ Int.

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Shell thinning affected by nozzle design, flux chemistry, heat transfer and steel flow was simulated through a mathematical model. Two nozzles were studied, the first, S60 with outer and inner diameters of 60 mm and 36 mm and the second, S73, with outer and inner diameters of 73 mm and 36 mm, respectively. Casting conditions include a casting speed of 1.3 m/min, use of a basic flux and a superheat of 36 K. Simulations included hypothetical isothermal casting conditions compared with casting conditions under thermal gradients. Simulation results indicated that the buoyancy forces, generated by thermal fields, exert a braking effect on the discharging jet whose magnitude was approximately 1/4 of the inertial forces. Shell growth along the curved mould walls suffers considerably thinning effects through the transport of sensible heat by convective mechanisms. Both nozzles induce shell thinning although, predictions of this mathematical model, using nozzle S73, indicate severe shell thinning effects in a region located in the inner radius side, down the second half of the mould length. This final shell thickness is very small making possible the existence of a strand breakout. Steel solidification along the flat mould walls leads to thick and uniform shells using either of these nozzles. The present numerical results indicate that in the field of flux design steel chemistry must be taken into account together with nozzle design.

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“…This is most important in thin slab funnel type molds, which operate at high casting speeds in confined volumes. Controlling turbulence is also important in order to avoid (1) mold flux entrainment which can transform to slivers in the final product 1,2) (2) to avoid meniscus instability, 3,4) (3) to evenly distribute heat transfer for uniform shell growth 5) and (4) to attain steady flow conditions. Some slab casting submerged nozzle designs induce strong meniscus instability and high amplitude oscillations of liquid steel in the mold.…”

Section: Introductionmentioning

confidence: 99%

Design of a Submerged Entry Nozzle for Thin Slab Molds Operating at High Casting Speeds

et al. 2012

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A submerged entry nozzle (SEN) for thin slab casters operating at casting speeds as high as 7.5 m/minute was developed based on fundamental grounds of boundary-layer theory and water modeling experiments. Experimental techniques included tracer injection to observe overall fluid flow patterns, high speed video camera and image analysis to follow dynamic changes of meniscus levels and particle image velocimetry to measure water speeds in the mold. This design was compared with two other SEN designs of nozzles under current commercial use at various thin slab casters. Direct comparisons of mathematical simulations and experimental results among the three SEN's evidenced that this new SEN yields very stable flows which are independent from casting speed and nozzle immersion depth. Fluid flow developed by this SEN consists of a double roll pattern without generation of superficial vortices. The two other SEN's yield instable discharging jets due to and excessive shearing effects with the surrounding fluid inducing severe dissipation of kinetic energy which promotes severe tailing effects inducing strong meniscus oscillations. The proposed design has reported good industrial performances and a longer operating life because the slag protection belt suffers less wear thanks to smaller velocities of the bath in contact with the SEN wall.

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

Cited by 26 publications

References 16 publications

Transport Phenomena in a Beam-Blank Continuous Casting Mold with Two Types of Submerged Entry Nozzle

Transport Phenomena in a Beam-Blank Continuous Casting Mold with Two Types of Submerged Entry Nozzle

Shell Thinning Phenomena Affected by Heat Transfer, Nozzle Design and Flux Chemistry in Billets Moulds

Design of a Submerged Entry Nozzle for Thin Slab Molds Operating at High Casting Speeds

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