Detailed Convective Heat Transfer at the Endwalls of Pin Fin, BCC, TKD and Octet Lattice-Based Cooling Channels

This study presents detailed endwall convective heat transfer measurements for four lattice topologies—pin-fins, body-centered cubic (BCC), tetrakaidecahedron (TKD), and Octet—arranged in inline configurations within a square duct. Each topology was tested in two configurations: continuous and discretely placed unit cells along the flow direction, resulting in a total of eight test articles. Transient liquid crystal thermography technique has been employed to determine local convection heat transfer coefficient resulting from the sole contribution of fluid dynamics in lattice-based channels. The test articles were additively manufactured in a low thermal conductivity and low thermal diffusivity resin and installed in a duct (AR 1:1) representative of the mid-chord region of high-pressure turbine blades. Experiments were conducted for Reynolds numbers between 10,000 and 30,000. Heat transfer results are presented as normalized Nusselt number maps and spanwise-averaged profiles, revealing periodicity in unit cell's thermal performance. TKD and Octet topologies exhibited the highest convective heat transfer, while BCC demonstrated superior thermal-hydraulic performance. These results offer valuable benchmarks for computational studies using periodic boundary conditions in fluid-only domains.