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Communication Dans Un Congrès Année : 2014

Numerical simulation of liquid metal infiltration and solidification inside a capillary tube

Résumé

A metal foam is a porous structure whose solid matrix has a large fraction of interconnected cells. The objective of our study is to define a new manufacturing process via casting that produces homogenous open cell metal foams. This comes down to studying the infiltration and solidification process of a liquid metal inside a porous mould. The metal foams are characterized by their high porosity and permeability values; thus, the size of the mould pore is small enough to be considered as a capillary tube. Therefore, the focus of this paper is on modelling and numerical simulation at a local scale of the infiltration and solidification of liquid metal inside a capillary tube. The main difficulty lies in the presence of 4 phases; mould, air, liquid and solid metal: a one-domain approach is chosen in the modelling of the problem. We subsequently obtained one set of equations as a function of two volumetric fractions: the metal/air fraction in the pore and the liquid fraction in the metal. Before the solidification starts, the liquid metal infiltrates the capillary thus the liquid metal-gas interface must be tracked. This is done implicitly using the VOF (Volume Of Fluid) method, where the advection equation of the volumetric metal fraction is coupled to the Navier-Stokes equation. The solidification process of the liquid metal is accounted for using the enthalpy-porosity approach. In addition, to ensure a zero velocity field in the mould and in the solid metal, two penalty coefficients as a function of the phase indicators were added to the momentum equation. The above mathematical model is implemented in a CFD tool: OpenFOAM. A numerical validation is performed by comparing the numerical results with well-known solutions of test cases. Then, the numerical results of the liquid aluminium solidification are compared to the fluidity tests carried out experimentally. Subsequently, a numerical parametrical study enabled us to find the relationships between the distance flowed by the liquid before its solidification and the infiltration time as function of the pressure difference, heat transfer coefficient and metal superheat. In our future work, we will derive a macroscopic model at the mould scale by up-scaling: the volume-averaged equations will be obtained from the local scale model using the volume averaging method. Then, the numerical results will be compared to the metal foam casting tests.
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Dates et versions

hal-01809827 , version 1 (07-06-2018)

Identifiants

  • HAL Id : hal-01809827 , version 1

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Nadine Moussa, Hervé Duval, Dominique Gobin, Benoît Goyeau. Numerical simulation of liquid metal infiltration and solidification inside a capillary tube. HEFAT2014 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Jul 2014, Orlando, United States. ⟨hal-01809827⟩
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