Characterization of Air Flow Through Sintered Metal Foams

Abstract

This study investigates air flow in metallic foams, which are produced by the slip reaction foam sintering (SRFS) process. It was conducted as part of the collaborative research center (SFB) 561 “Thermally Highly Loaded, Porous and Cooled Multi-Layer Systems for Combined Cycle Power Plants.” The flow through a porous medium is analyzed by Darcy’s equation with the Dupuit/Forchheimer extension. All measurements can be described very well by this equation and permeability and inertial coefficients are obtained for a large quantity of samples with different base materials and different porosities. A threshold porosity of 70% is observed, above which the pressure loss significantly starts sinking with porosity. Additionally, it was found that the permeability was anisotropic. Permeability is lower in the direction of gravity during foaming. Scattering in the data of the permeability and inertial coefficients versus the porosity is observed and discussed.

The permeability of replicated microcellular structures in the Darcy regime

“…A significant part of these works has seen the utilization of the pressure–velocity data and fluid flow properties in estimating the permeability of the porous medium using the above expressions. Despite the unique and combined characteristics of high pore volume, high surface area and different pore topologies offered by porous metals over packed beds, applicable theories in the use of the above expressions to reliably describe fluid flow behavior in porous metallic structures exist …”

“…Despite the unique and combined characteristics of high pore volume, high surface area and different pore topologies offered by porous metals over packed beds, 1,12 applicable theories in the use of the above expressions to reliably describe fluid flow behavior in porous metallic structures exist. [24][25][26][27][28][29][30][31][32][33] Understanding the influence of the pore-structure related properties (porosity, pore diameter sizes, pore openings, and specific surfaces) on the permeability of these structures ( Figure 1) Figure 2a presents close agreements between experimentally measured and CFD modeled data 2 for samples of similar pore sizes (2.0-2.5) but differentiated by their applied differential pressures during casting; showing a varying degree in the sizes of their pore diameter openings. Table 1 presents these changes in porestructure related properties and flow information in the inertial dominated flow.…”

Optimized volumetric solar receiver: Thermal performance prediction and experimental validation

“…The analysis of the pressure drop inside the porous sample has been performed adapting the experimental setup according to Reutter et al [14] and shown in Fig. 6.…”

“…The latter is calculated taking into account the pressure difference measured with an accuracy of ±1% by two sensors that are placed before and behind the orifice. The pressure drop across the sample has been measured, together with the air temperature, using two additional sensors placed right next to the porous sample and presenting an accuracy of ±1% [14].…”

“…Measurements have been performed at constant temperature for different values of incoming mass flow rate, as reported below: The specific pressure drop (Dp/L) has been calculated according to Eq. (14). Error bars for the experimental results show a variation of ±3%, taking into account the accuracy of the instruments for the measurement of the outlet pressure and the standard deviation for each operational point.…”