CROSS ANALYSIS OF METAL FOAM DESIGN PARAMETERS FOR ACHIEVING DESIRED FLUID FLOW

摘要

This paper presents an experimental study of air flow through open cell metal foams for use as a thermal energy dissipating system. The goal of this paper is to identify the optimum configuration of metal foam design parameters for maximum flow. Four foam blocks were used in the study, representing a range of design parameters: material (copper or aluminum), pore size (5-10 pores per inch), and relative density (e = 0.875 - 0.952). The effects of pore size were isolated by comparing air flow through three aluminum foam blocks with constant density and varied pore size. A series of wind tunnel tests were performed to measure the velocity of air flowing through the foam as a function of the free stream air velocity, ranging from 0 to 17.4 mph (7.5 m/s). Results indicated smaller pore sizes and larger densities decreased the amount of airflow through the foam. However, one foam sample produced results that did not fit this trend. Further investigation found this was likely due to the differences in the cross-sectional geometry of the foam ligaments. The ligament geometry, affected by density and manufacturing method, was not constant and not initially considered as a variable of interest. The cross-section shape of the ligaments was found to vary from a rounded triangular shape to a triangle shape with concave surfaces, increasing the amount of drag in the airflow through the sample.