Effect of porosity and injection ratio on the performance of transpiration cooling through gyroids

This paper presents experimental measurements of adiabatic effectiveness for three transpiration cooling porosities (ϕ = 0.3, 0.4, and 0.5) constructed from Gyroid lattice structures. To the authors' knowledge, this is the first use of a Triply Periodic Minimal Surface (TPMS) function to produce transpiration test coupons of varying porosity. Polymer Gyroid lattice structures were successfully printed using Stereolithography (SLA) down to ϕ =0.3 for a print resolution of 25 microns and unit cell size of 2 mm. Cooling performance was measured in a small-scale wind tunnel. High-resolution Infrared Thermography was used to determine wall temperatures downstream of the porous section. When tested at both common blowing ratios (M=0.029, 0.048 and 0.062) and common injection ratios (F=0.010, 0.017 and 0.022) the cooling performance was found to be dependent on porosity for constant M but not for constant F. Having determined F as the more important parameter for comparison, results were presented alongside transpiration and effusion data from literature.