Latifa Begum

A Numerical Study of 3D Turbulent Melt Flow and Solidification in a Direct Chill Slab Caster with an Open-Top Melt Feeding System

A 3D control-volume based finite-difference model has been developed to simulate coupled turbulent melt flow and solidification phenomena for a semi-continuous direct chill slab casting of an aluminum alloy (AA-1050). The model considered an open-top melt delivery system for a hot-top mold. The model was verified with the experimental solidification front measurements and a reasonable agreement was found. The computations were carried out by varying important process parameters such as casting speed, inlet melt superheat, and mold–metal contact effective heat transfer coefficient in order to understand their effects on the solidification and cooling behavior of AA-1050.

A Numerical Study of 3D Turbulent Melt Flow and Solidification in a Direct Chill Slab Caster with a Porous Combo Bag Melt Distributor

A 3D turbulent melt flow and solidification of an aluminum alloy (AA-1050) for an industrial-sized direct chill slab casting process is modeled. The melt is delivered through a rectangular submerged nozzle and a non-deformable combo bag fitted with a bottom porous filter. The non-Darcian model, incorporating the Brinkman and Forchheimer extensions, is used to characterize the turbulent melt flow behavior passing through the porous filter. The casting speed and the effective heat transfer coefficient at the metal–mold contact region within the mold are varied. The above two parameters are found to have significant influence on the solidification process.

Modeling of Transport Phenomena in Low-Head Direct-Chill Caster for AA7050 Alloy

As an extension of earlier work, a three-dimensional numerical model has been developed for an industrial-scale low-head direct-chill slab casting process for the long freezing range aluminum alloy AA7050. The model has taken into account the coupled nature of the turbulent melt flow and the solidification heat transfer aspect of the direct-chill casting process. Computer simulations were performed to predict the velocity and temperature fields, the sump profile, the mushy thickness, and the shell thickness at the exit of the mold. Specifically, the aforementioned results were obtained for four casting speeds, varying from 60 to 180  mm/min, for three metal–mold effective heat transfer boundary conditions, varying from 1.0 to 4.0  kW/(m2·K), and for three pouring temperatures of inlet melt, namely, 645, 661, and 693°C. A stepwise change of the cooling water temperature in the mold and impingement and free-streaming regions, were considered to reflect the temperature history of the cooling water conditions...

Three-Dimensional Modeling of Direct Chill Caster with Partial Porous Plate

A three-dimensional control-volume-based finite difference code is developed to simulate a vertical direct chill casting process for aluminum alloy AA-1050. The rectangular slab caster is fitted with a porous plate occupying 50% of the width of the ingot and is placed near the top in the central region. The turbulence in the liquid sump is modeled employing a popular version of the low Reynolds number κ-e model. The enthalpy–porosity technique is used to solve the coupled melt flow and solidification heat transfer problem. To model the porous plate, the Brinkman–Forchheimer extended Darcy equation is considered. The code is first verified with the available experimental solidification profile data for a direct chill caster of a rolling ingot AA-3104. The effects of casting speed and heat transfer coefficient at the metal-mold contact region on solidification characteristics are investigated. By varying the latent heat of solidification of the said alloy, sensitivity analysis is also carried out. The tempe...

3D CFD study of low-head direct chill slab casting of aluminium alloy AA3003

A 3D control volume-based finite difference model was developed to simulate an industrial scale low-head direct chill (DC) slab casting process for the intermediate freezing range aluminium alloy AA3003. The model took into account the coupled nature of the turbulent melt flow and solidification heat transfer aspect of the direct chill casting (DCC) process. The model was used to predict the velocity and temperature fields. By post-processing, the temperature results, the sump depth and the mushy thickness at the centre of the slab and the shell thickness at the exit of the mould were calculated. Specifically, three important process parameters, namely, casting speed, melt superheat and effective heat transfer coefficient at the metal-mould contact region were varied in the range of 60 to 180 mm/min, 16 to 64°C, and 1.0 to 4.0 kW/m²K, respectively. Consistent with the industrial practice, in the mould, in the impingement and the free streaming regions, a step-wise increase of the cooling water temperature was considered. The predicted results were then critically analysed and discussed.

Low-head direct chill slab casting of aluminium alloy AA-6061: 3-D numerical study

An industrial-sized vertical low-head direct chill slab casting process for the aluminium alloy AA-6061 is modelled by taking into account the 3-D turbulent melt flow and heat transfer in the liquid sump and by giving proper consideration of the mushy region solidification aspect of the process. Computed results for the steady-state phase of the casting process are presented for four casting speeds, varying from 60 to 180 mm min−1, for three metal–mould effective heat transfer boundary conditions, varying from 1.0 to 4.0 kW m−2 K−1 and for three inlet melt superheats of 16, 32 and 64 °C. A step-wise change of the cooling water temperature in the mould, impingement and free streaming regions are considered to reflect the actual operations. Detailed results in the form of velocity and temperature fields, solidification shell and mushy region thickness, sump depth and temperature profiles at four critical locations along the caster are provided and discussed.

A Comparison Between 3-D Thermal Model and 3-D CFD Model for Vertical DC Casting of Rolling Ingots of Aluminum Alloy 7050

In this study, first a 3-D thermal model is developed for an open top, vertical direct chill (DC) casting process of rolling slabs (ingots) by taking into account the casting speed in the form of slag flow in the thermal connective-diffusion equation. The mushy region solidification characteristics of the process are accounted for through the implementation of the enthalpy porosity technique. The thermal model is later extended to a 3-D CFD model to account for the coupled turbulent heat transfer and solidification aspect of the process. Both models simulate an industrial-sized, hot-top type vertical Direct Chill (DC) slab caster for high strength aluminum alloy AA-7050. A staggered control volume based finite-difference scheme is used to solve the modeled equations and the associated boundary conditions. In the CFD model, the turbulent aspects of flow and solidification heat transfer are modeled using a low Reynolds number version of the k–e eddy viscosity approach. Computed results for the steady-state phase of the casting process are presented for four casting speeds varying from 60 to 180 mm/min for a fixed inlet melt superheat of 32°C. Simulation results of the velocity and temperature fields and heat fluxes along the caster surface are presented for the CFD model and the shell thickness and sump depth are compared between the CFD and thermal models.Copyright