Effect of Fluid Bypassing on the Experimentally Obtained Darcy and Non-Darcy Permeability Parameters of Ceramic Foam Filters

Abstract

SHAHIN AKBARNEJAD, MOHSEN SAFFARI POUR, LAGE TORD INGEMAR JONSSON, and PÄ R GÖ RAN JÖ NSSONCeramic foam filters (CFFs) are used to remove solid particles and inclusions from molten metal. In general, molten metal which is poured on the top of a CFF needs to reach a certain height to build the required pressure (metal head) to prime the filter. To estimate the required metal head, it is necessary to obtain permeability coefficients using permeametry experiments. It has been mentioned in the literature that to avoid fluid bypassing, during permeametry, samples need to be sealed. However, the effect of fluid bypassing on the experimentally obtained pressure gradients seems not to be explored. Therefore, in this research, the focus was on studying the effect of fluid bypassing on the experimentally obtained pressure gradients as well as the empirically obtained Darcy and non-Darcy permeability coefficients. Specifically, the aim of the research was to investigate the effect of fluid bypassing on the liquid permeability of 30, 50, and 80 pores per inch (PPI) commercial alumina CFFs. In addition, the experimental data were compared to the numerically modeled findings. Both studies showed that no sealing results in extremely poor estimates of the pressure gradients and Darcy and non-Darcy permeability coefficients for all studied filters. The average deviations between the pressure gradients of the sealed and unsealed 30, 50, and 80 PPI samples were calculated to be 57.2, 56.8, and 61.3 pct. The deviations between the Darcy coefficients of the sealed and unsealed 30, 50, and 80 PPI samples found to be 9, 20, and 31 pct. The deviations between the non-Darcy coefficients of the sealed and unsealed 30, 50, and 80 PPI samples were calculated to be 59, 58, and 63 pct.

Three-Dimensional Digital Reconstruction of Ti2AlC Ceramic Foams Produced by the Gelcast Method

“…Gas compressibility effects were also non-critical due to the very low Mach number of the systems. In the work by Akbarnejad et al [33], the effect of fluid flow on the resulting pressure gradient was studied during permeametry experiments on unsealed ceramic foam filters. They empirically derived Darcy and non-Darcy permeability coefficients based on Forchheimer's equation.…”

Determination of Permeability and Inertial Coefficients of Sintered Metal Porous Media Using an Isothermal Chamber

“…[5] Open-cell aluminum foams Water Medraj et al, (2007) [6] metallic foams Air Beavers & Sparrow, (1969) [11] Metallic fibers Liquid Beavers et al, (1973) [12] Packed beds of spheres Liquid Antoheet al, (1997) [14] Compressed aluminum porous matrices Poly-alpha-olefin fluid Air Dukhan & Minjeur, (2011) [15] open-cell aluminum foam Air Jin & Kai, (2008) [20] Open-cell metal foams Air Mancin et al, (2010) [21] aluminum open-cell foam Air Rodrigo et al, (2008) [24] Bronze sintered porous bearing Air Zhong et al, (2014) [28] Sintered metal porous media Air Dukhan & Ali, (2012) [33] open-cell aluminum foam Air Figure 4 shows the pneumatic circuit for the measurement. Akbarnejad et al [35] stated that if the test medium is not well sealed the measured parameters deviates greatly from its real value. In this work, the porous medium is placed in a cylindrical rubber and two end covers are used to compress the rubber.…”

“…Figure 4 shows the pneumatic circuit for the measurement. Akbarnejad et al [35] stated that if the test medium is not well sealed the measured parameters deviates greatly from its real value. In this work, the porous medium is placed in a cylindrical rubber and two end covers are used to compress the rubber.…”

Verification of Experimentally Determined Permeability and Form Coefficients of Al2O3 Ceramic Foam Filters (CFF) at High and Low Flow Velocity Using a CFD Model

“…where ρ is the fluid density (kg•m -3 ), ∇ the differential operator, u the velocity vector (m•s -1 ), ̅ the time-averaged mean velocity in the xi direction, P the pressure (Pa), and µ the dynamic viscosity (kg•m -1 •s -1 ) [4,[11][12][13]. The modelling of Reynolds stresses for solving the RANS equation is based on the Prandtl's mixing length theory and defining a two-layer algebraic model for the turbulent viscosity (eddy viscosity), which depends on the distance from the wall [12,14].…”