Endwall heat transfer characteristics of octahedron family lattice-frame materials

Abstract

Recent studies on traditional metal foam thick blocks suggest that much of the foam volume remains unused in heat dissipation and that the thinner configurations are more efficient in forced convection scenarios. Single cell thick lattice-frame configurations are attractive solutions to the problem of unused foam volume and can also be additively manufactured through Direct Metal Laser Sintering process while also offering superior load bearing capabilities. Due to the inherent nature of such single cell thick configurations, their unit cell topologies' footprint at the enclosing walls has significant effect in both local heat transfer coefficient distribution and net overall heat dissipation. This study presents detailed endwall heat transfer coefficient measurements for lattice-frame structure of Octet unit cell topology and compares its thermal performance with two other members of the Octahedron family, viz. Octa and V-Octet. Developing heat transfer was measured through transient liquid crystal thermography at the endwalls of a unity aspect ratio duct featuring five consecutive interconnected unit cells at a Reynolds number of 37,200. Relative to a smooth channel, the cell-based averaged Nusselt numbers for Octet, Octa and V-Octet were 2.96, 2.78 and 3.05 times, respectively.