Structure of turbulent flow in a slab mold

Abstract

The structure of the turbulent flow in a slab mold is studied using a water model, various experimental techniques, and mathematical simulations. The meniscus stability depends on the turbulence structure of the flow in the mold; mathematical simulations using the k-model and the Reynolds-stress model (RSM) indicate that the latter is better at predicting the meniscus profile for a given casting speed. Reynolds stresses and flow vorticity measured through the particle-image velocimetry (PIV) technique are very close to those predicted by the RSM model, and maximum and minimum values across the jet diameter are reported. The backflow in the upper side of the submerged entry nozzle (SEN) port (for a fixed SEN design) depends on the casting speed and disappears, increasing this process parameter. At low casting speeds, the jet does not report enough dissipation of energy, so the upper flow roll is able to reach the SEN port. At high casting speeds, the jet energy is strongly dissipated inside the SEN port, the narrow wall, and in the mold corner, weakening the momentum transfer of the upper flow roll, which is unable to reach the SEN port. At low casting speeds, meniscus instability is observed very close to the SEN, while at high casting speeds, this instability is observed in the mold corner. An optimum casting speed is reported where complete meniscus stability was observed. The flow structure at the free surface indicates a composite structure of islands with large gradients of velocity at high casting speeds. These velocity gradients are responsible for the meniscus instability.

Explicit Modelling of Slag Infiltration and Shell Formation during Mould Oscillation in Continuous Casting

“…A similar flow pattern was found for all casting speeds simulated, with rolls developing above and below the main discharging jet leaving the SEN, which agrees with previously reported findings. 17) The effect of changes in casting speed is also consistent with previous numerical and experimental observations, showing increases in velocity magnitude in the jet with increasing casting speed. 19) Velocities in the slag bed and at the steel-slag interface, are successfully calculated with this technique due to the multiphase approach defined by Eqs.…”

“…This model calculates the flow dynamics of molten steel, air and slag within the mould, building on a prior more limited model. 17) Direct infiltration of slag into the shell-mould gap is achieved by coupling the Navier-Stokes equations for compressible viscous flow with a multiphase tracking technique known as volume of fluid (VOF) 18) and a k-e turbulence model. 17,19) ... (1) ... (2) All variables are defined in the list of symbols at the end of the manuscript.…”

“…17) Direct infiltration of slag into the shell-mould gap is achieved by coupling the Navier-Stokes equations for compressible viscous flow with a multiphase tracking technique known as volume of fluid (VOF) 18) and a k-e turbulence model. 17,19) ... (1) ... (2) All variables are defined in the list of symbols at the end of the manuscript. Calculation of the slag-metal interface is attained through the Continuum Surface Force (CSF) model developed by Brackbill et al,20) which is added to the momentum equation through the source term S s .…”

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

“…Additional experiments consisted in the injection of a red dye tracer in the upper part of the nozzle to observe the expansion of the jet as well as the mixing patterns recorded by a digital [17] is suitable. The reason behind this choice is based on the simplicity of this model, its capability to predict acceptably well complex engineering flows, [18][19][20] and its widespread knowledge by the fluid mechanics community. Essentially, the model consists of simultaneously solving the continuity, momentum, kinetic energy, and dissipation rate of the kinetic energy equations.…”

Transient Thermo-fluid and Solidification Behaviors in Continuous Casting Mold: Evolution Phenomena

“…[6][7][8] Banderas et al 9) characterized the periodical behavior of turbulent flows using the large eddy simulation (LES) computational approach, which compared with the Digital Particle Image Velocimetry (DPIV) measurement. A similar model by Lopez et al 10) included the effects of casting speed on fluid-flow structure, meniscus topography and kinetic energy distri- bution. Several computational models of heat transfer and solidification have focused on the formation of oscillation marks on the surface of continuously cast slabs.…”