An Analysis Framework of Additively Manufactured Deterministic Porous Structures for Transpiration Cooling

Transpiration cooling has seen a resurgence of interest for thermal protection in hypersonic flight, rocket engine liners, and gas turbines. To date, materials for transpiration cooling have been restricted to porous ceramic composites and sintered metal foams. Advances in additive manufacturing have enabled the creation of architected lattices, which have deterministic mesostructures. One such family of lattices are triply-periodic minimal surfaces (TPMS), which are continuous, analytically-defined, repeating 3D geometries. Additively-manufactured metal TPMS structures are already being studied for biomedical applications and it is proposed that they could offer several advantages for transpiration cooling as well: high surface area-to-volume ratio, pore inter-connectivity, and mechanical strength. In this work, the fluid flow behavior through a gyroid TPMS lattice is investigated through computational fluid dynamics simulation, using the lattice Boltzmann method. A comparison is made between ideal geometry and the as-printed geometry of a sample fabricated with laser powder bed fusion and characterized using x-ray computed tomography. The as-printed part matched the design porosity to within 1%, while the as-printed permeability was found to be 14.8% lower than that of the ideal geometry. The results of this research will assist in developing a methodology for the design optimization via performance simulation of these structures to meet fluid flow requirements for transpiration cooling applications.