Effects of Lattice Orientation Angle on TPMS-Based Transpiration Cooling

Abstract

Establishing a continuous cooling film is an effective way to thermally protect hot-gas path components of gas turbines. For aero-engines, effusion cooling is the state-of-the-art method for developing cooling films. However, the cooling film generated by this method is far from ideal, as discrete miniature cooling air jets exiting from effusion cooling holes leave large gaps between cooling holes without adequate cooling film protection. Furthermore, effusion cooling jets can experience strong liftoff from component surfaces and are subsequently diluted due to mixing with the main flow. Recent advances in additive manufacturing (AM) technologies have enabled the fabrication of porous materials with precisely engineered lattice structures, significantly enhancing the film cooling effectiveness of hot-gas path components through transpiration cooling. A prior study has demonstrated highly promising transpiration cooling results by using a family of lattice geometries referred to as triply periodic minimal surface (TPMS) lattices. The present study experimentally investigates the influence of various TPMS lattice orientations on the film cooling effectiveness. Three types of TPMS structures, namely, diamond, Koch, and gyroid, are compared to demonstrate that the TPMS lattice orientation angle affects transpiration cooling performance, with different levels of sensitivity according to the TPMS structure. The TPMS lattice structures studied in this investigation are fabricated by stereolithography (SLA) three-dimensional printing. The adiabatic cooling film effectiveness (AFE) is measured using pressure sensitive paint (PSP).