Numerical investigation of pressure drop and heat transfer through reconstructed metal foams and comparison against experiments

摘要

Direct numerical simulation of transport in foam materials can benefit from realistic representations of the porous-medium geometry generated by employing non-destructive 3D imaging techniques. X-ray microtomography employs computer-processed X-rays to produce tomographic images or slices of specific regions of the object under investigation, and is ideally suited for imaging opaque and intricate porous media. In this work, we employ micro-CT for numerical analysis of air flow and convection through four different high-porosity copper foams. All four foam samples exhibit approximately the same relative density (6.4% - 6.6% solid volume fraction), but have different pore densities (5, 10, 20, and 40 pores per inch, PPI). A commercial micro-computed tomography scanner is employed for scanning the 3D microstructure of the foams at a resolution of 20 μm, yielding stacks of two-dimensional images. These images are processed in order to reconstruct and mesh the real, random structure of the foams, upon which simulations are conducted of forced convection through the pore spaces of the foam samples. The pressure drop values from this μCT based CFD analysis are compared against prior experimental results; the computational interfacial heat transfer results are compared against the values predicted by an empirical correlation previously reported, revealing excellent agreement between the numerical and experimental/empirical hydraulic and thermal results, thus highlighting the efficacy of this novel approach.