Experimental Study on Flow and Thermal Transport in Additively Manufactured Lattices Based on Cube-Shaped Unit Cell

Abstract

This paper presents the convective heat transfer coefficient of cubic lattices under both buoyancy-induced and forced convection. Additionally, it examines the effective thermal conductivity, permeability, and inertial coefficient of a cubic unit cell of porosity ~0.87. The test specimens were additively manufactured using stainless steel 420 (with 40% bronze infiltration) using the binder jetting technique. In the buoyancy-driven convection experiments, three different aspect ratios (width/height) varying from 0.5 to 2 were tested across three different heating orientations, viz. bottom wall (0°), side wall (90°), and top wall (180°). The lattice with the lowest aspect ratio had the highest convective heat transfer coefficient in all three heating orientations. The forced convection heat transfer coefficient was determined for an AM part comprising 10 x 10 cubic unit cell array in the plane perpendicular to the flow and 20 unit cells in the streamwise direction. Additionally, the flow characteristics of the cubic lattice were characterized through permeability (K) and inertial coefficient (Cf), determined by conducting separate pressure drop experiments over a wide range of flow velocities. The thermal hydraulic performance of the cubic lattice was assessed by combining the periodic regime convective heat transfer coefficient with the pressure drop data obtained from the experimentally determined values of K and Cf. The comprehensive characterization of flow and thermal transport, including K and Cf, along with hsf, keff, presented in this paper, provides a robust foundation for their application in volume-averaged computations for detailed parametric study.