Fluid-flow and endwall heat-transfer characteristics of an ultralight lattice-frame material

This paper describes an experimental study of the pressure loss and endwall heat transfer in a highly porous, ultralightweight, multifunctional lattice-frame material (LFM) subjected to forced air convection. The influence of LFM morphology on the endwall flow and heat transfer patterns in a unit cell is examined in detail. Depending on the orientation of the LFM, the pressure loss across a unit cell was found to be between about 30% and 60% of the dynamic pressure over a wide range of Reynolds numbers. For the two selected orientations, the LFM has almost the same overall heat transfer performance. Detailed endwall surface heat transfer distributions were obtained using thermochromic liquid crystals (TLCs). The results reveal that the local endwall heat transfer was sensitive to details such as the location of vertices and the inclination angle of struts. High heat transfer regions were clearly observed around the vertices due to the formation of horseshoe vortices and behind the inclined and/or yawed struts. It was also found that the use of high conductivity materials such as aluminum alloy for the struts enhances the rate of heat transfer by a factor of approximately 2.5 when compared to using a low conductivity material such as polycarbonate. (C) 2003 Elsevier Ltd. All rights reserved.