TPMS-based transpiration cooling for film cooling enhancement

The present study experimentally evaluates the adiabatic film cooling effectiveness of a gaseous transpiration cooling concept based on a family of nature-inspired triply periodic minimal surface (TPMS) lattices that are enabled by additive manufacturing. The performances of TPMS-based transpiration cooling designs are directly compared to those of a typical effusion cooling design featuring an array of discrete cooling holes, the state-ofthe-art cooling technology for aerospace gas turbines. Specifically, three solid-network TPMS lattice structures with porosities at 30, 40, and 50% are additively manufactured and their adiabatic film cooling effectiveness values are determined using a dual-luminophore pressure sensitive paint (PSP) method based on heat and mass transfer analogy. The experimental results indicate that, as the cooling film grows downstream, the adiabatic film cooling effectiveness of the TPMS lattice structure of 50% porosity approaches 0.77, 0.88, and 0.91 at low, medium, and high coolant flow rates, respectively. The adiabatic film cooling effectiveness values achieved with the TPMS-based transpiration cooling designs of this work reach five times those of conventional effusion cooling under corresponding coolant consumption rates. The findings of the present study suggest that TPMS-based transpiration cooling as a promising alternative to effusion cooling could bring significant efficiency gains to gas turbine engines by reducing cooling air consumptions, since it offers a higher adiabatic film cooling effectiveness, creates a more complete and uniform film coverage, and mitigates the film lift-off propensity at high blowing ratios. Furthermore, the distinctive features of TPMS lattices enable efficient interior cooling, provide high mechanical strengths, and facilitate additive manufacturing.