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Influence of the Strut Shape of Open-Cell Foams on Hydraulic Tortuosity, Permeability and Removal Efficiency for non-metallic Inclusions during Filtration of Liquid AluminumWednesday (07.10.2020) 16:20 - 16:40
This article presents a numerical study on the sensitivity of the performance of open-cell foams for the depth filtration of liquid metals with respect to an elliptical elongation or flattening of the cross-sectional shape of the filter struts in the flow direction. Foams are modeled using an artificially generated beam model convolved with different anisotropic Gaussian kernels. The aspect ratio is varied in the range 0.25 to 4 by adjusting the variance of the Gaussian in every direction accordingly. The filter surfaces are obtained as a level-set on the resulting 3D grayscale image using different threshold values for filters with porosities between 70 and 90%. The performance of the different structures is evaluated by observing the velocity field, the pressure drop, the viscous and inertial permeability coefficients, the hydraulic tortuosity as well as the filtration coefficient, which are obtained from detailed pore-scale simulations of the melt flow and inclusions transport. The simulations are set up for process conditions typical for aluminum filtration during continuous casting, i.e. a pore count of 30PPI, a melt temperature of 730°C, a melt velocity of 10mm/s, and alumina inclusions with a size range of 10 to 40µm. The results show a significant influence of the cross-sectional shape of the struts on the effective properties related to the metal melt filtration and are used to draw conclusions regarding the design of the filter geometries.