An experimentally validated and parameterized periodic unit-cell reconstruction of open-cell foams

Abstract

The physical behavior of open-cell foams depends on their microscopic structure. An open-cell geometrical model is proposed, which can serve as the basis for a future macroscopic analysis. The strut geometry is of particular interest, as it is reported to have substantial influence on the occurring thermo-hydraulic and mechanical phenomena. Axial strut size variation, as well as the porosity dependence of shape is quantified and included in a geometrical model. The foam is generated by placing the struts on an elongated tetrakaidecahedron. The required input parameters for the model are two cell dimensions, corresponding to the mean transverse and conjugate diameters of the ellipse encompassing a cell, and the strut cross-sectional surface area at its midpoint between two nodes. The foam geometry is generated iteratively, as porosity is used as validation. A high resolution micro-computed tomography scan is performed to measure the three parameters, the resulting porosity and surface-to-volume ratio. This allows to validate the model. The predictions are found to be within measurement accuracy. A numerical implementation of the model in the preprocessor of a commercial CFD package is demonstrated.

Comparison of metal foam heat exchangers to a finned heat exchanger for low Reynolds number applications

“…For the 10 and 20 PPI foams the characteristics were determined via lCT scanning by De Jaeger et al [44] on existing aluminum foam samples (PPI = pores per linear inch; also referred to as pore density). The macroscopic characteristics of the four other foams are calculated from the microscopic foam parameters provided by the manufacturer using the periodic unit cell reconstruction of open-cell foams developed by De Jaeger et al [44]. / is the volumetric porosity (defined as the ratio of the air volume to the total volume) and r o is the specific surface area.…”

A new prediction model for the effective thermal conductivity of high porosity open-cell metal foams

“…a 1 ¼ 2.01 due to two considerations: (1) in the calculation of ligament perimeter, one term (a 1 À 2) exists in the denominator [33], and setting a 1 at 2.01 instead of 2 can avoid being divided by zero; (2) as will be discussed in Section 2.2, any variation in a 1 , if 2 a 1 3, has no detectable influence on the ETC of metal foams. Thus a 1 ¼ 2.01 is justified.…”

On the effective thermal conductivity of aluminum metal foams: Review and improvement of the available empirical and analytical models

“…At the moment, a significant effort is devoted to describing the foam structure in a more realistic way: from this perspective, X-ray computed microtomography (μ-CT) appears a promising and appealing approach to be coupled to numerical simulations. The literature includes several works dealing with μ-CT, not only limited to metal foams or thermal conductivity estimations [1,3,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45]. The literature offers a wide set of analytical and empirical correlations for the estimation of the effective thermal conductivity of metal foams.…”