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Wind-tunnel steady-state unidirectional pressure-drop measurements for airflow through nine compressed and uncompressed isotropic open-cell aluminum foam samples, having different porosities and pore densities, were undertaken. The compressed foam produced significantly higher pressure drop. which increased with increasing Darcian velocity following the quadratic Forchheimer equation. The permeability and the inertia coefficient data for the compressed for showed less scatter compared to those for the uncompressed foam. Both were correlated using an Ergun-like equation, with the correlation being better for the permeability. The permeability correlation predicted the results of some previous studies very well. The friction factor correlated well with the Reynolds number. [DOI: 10.1115/1.2236132] Keywords: pressure drop, permeability, metal foam, porous media

Experimental Frossling numbers are presented for two aluminum castings of ice-roughened NACA 0012 airfoil surfaces at 0-deg angle of attack for chord Reynolds number ranging from 4.00 x [10.sup.5] to 1.54 x [10.sup.6]. The castings were meticulously obtained from actual ice accretions representing mildly rough glaze and rough glaze ice with horns. A modified investment casting technique was used to capture all of the surface roughness details. The rough glaze ice with horns produced higher heat-transfer rates than those for the mildly rough glaze ice, especially at the horns. Immediately downstream of the horns, stagnation air gaps resulted and caused lower heat-transfer coefficients. For both types of ice, higher Reynolds numbers in general produced higher heat-transfer coefficients. For the same chord Reynolds number and at the same position on the airfoil, the Frossling numbers were generally higher than those for the smooth case and those for the hemispherical roughness elements of previous studies. A maximum increase of approximately 306% over the smooth case and 192% over the dense hemispherical roughness case was recorded at one rough glaze ice horn. This work provides some directly measured values of the Frossling number needed to improve the prediction of some icing codes. Such icing codes help in the effective design of some deicing systems of aircraft.

Experimental Stanton numbers for seven aluminium model castings of ice-roughened surfaces in parallel air flow for Rex are presented. They were generally higher than those for previous studies with hemispherical and truncated cone roughness elements. The rime feather ice roughness generally produced the highest rates of heat transfer.

Metal and graphite foam are relatively new types of porous materials characterized by having high-solid phase conductivities. In many cooling applications of these materials, including high-power electronics, low-conductivity fluids flow through them, e.g., air. A simple approximate engineering solution for the convection heat transfer inside a two-dimensional rectangular porous media subjected to constant heat flux on one side is presented. The conduction in the fluid is set to zero, and for simplicity, a plug flow is considered. As a result, the non-local-thermal equilibrium equations are significantly simplified and solved. The solid and fluid temperatures decay in what looks like an exponential fashion as the distance from the heated wall increases. The results are in good agreement with one more complex analytical solution in the literature, in the region far from the heated wall only. [DOI: 10.1115/1.3143947] Keywords: convection, heat sink, metal foam, graphite foam, electronics cooling

A new study investigates the acceleration effect on the rate of heat transfer from stochastically accreted ice-roughened surfaces. Seven models of different types of ice accretions were tested for free stream velocities of 9.4, 20.7 and 32.6 m/s in a wind tunnel and at inclination angles between 5 deg and 41 deg. The study examines the acceleration effect on the Stanton numbers.