Air flow through confined metal foam passage: Experimental investigation and mathematical modelling

This paper deals with flow behaviour through a confined passage filled with metal foams (MFs). Two sets (four samples) of aluminium foams of 20 and 40 ppi pore densities with 9-11% and 12-16% relative densities (RD) individually (as per supplier's specification) were used for the study. Former RD belonged to uncompressed metal foams whereas the later was achieved by unidirectional compression of metal foam of 6-8% RD. Measured porosities of the uncompressed 20 and 40 ppi MF samples were equal, which was 0.88. However, measured porosities were 0.83 and 0.86 for compressed 20 and 40 ppi MF samples. Flow characteristics of both compressed and uncompressed samples were experimentally measured. Fourie-Plessis's representative unit cell (RUC) model was used as an analytical tool for estimating pressure drop gradient through MFs because of its simplistic approach and independency from flow characteristics. Possible encasing wall effect on pressure drop was theoretically conducted. Due to a significant difference in estimated and experimentally obtained pressure drop gradient, authors have proposed a modification in the RUC model. The modified version of the RUC model was able to estimate pressure drop gradient of the uncompressed samples with a considerably higher accuracy.