Impact of Triply Periodic Minimal Surface Structure Unit Cell Size on Transpiration Cooling

Transpiration cooling is a highly promising technology for use in thermal management in modern gas-turbine-based aeroengines, providing superior cooling effectiveness compared to state-of-the-art effusion cooling methods. However, conventional porous media such as metallic foams and sintered metals, when used for transpiration cooling, face challenges in achieving desired engineering properties, such as surface texture, mechanical strength, and porosity profile. To achieve the full potential of transpiration cooling by overcoming the challenges inherent in conventional porous media, a precisely engineered deterministic porous medium is desirable. Recent advancements in additive manufacturing have enabled the fabrication of porous media with highly precise lattice structures. Among candidate lattice structures, triply periodic minimal surface (TPMS) structures are considered ideal due to their superior mechanical strengths and fully interconnected, periodic internal channels and external texture patterns to facilitate cooling film development. This study aims to investigate the impact of unit cell size of TPMS lattices on adiabatic film cooling effectiveness using binary pressure-sensitive paint (PSP). Diamond-type TPMS lattices of a fixed actual porosity (36%) but of three distinct unit cell sizes (1.9, 2.5, and 3.1 mm) were examined at three injection ratios ([Formula: see text], 1.14%, and 1.60%). Results show that smaller unit cell sizes lead to more effective and more uniform cooling films. Enhanced transpiration cooling effectiveness at smaller unit sizes might be attributed to shallower surface voids and reduced lateral flow within the porous medium. The findings are expected to guide the design of TPMS-based transpiration cooling systems.