Optimized Permeability of Microporous Foam for Transpiration Cooling in Hypersonic Leading Edge

• Published in: Journal of thermophysics and heat transfer 2022-10, Vol.36 (4), p.907-919
• Main Authors: Dickstein, Dylan, Donghyun Ko, Danny, Nadvornick, Warren, Jain, Karan, Holdheim, Saurin, Sungtaek Ju, Yongho, Ghoniem, Nasr
• Format: Article
• Language: English
• Subjects: Capillarity; Coolant pumps; Cooling; Diameters; Effectiveness; Heat flux; Heat transfer; Hypersonic aircraft; Leading edges; Nose tips; Optimization; Permeability; Porosity; Radius of curvature; Stagnation point; Sweat cooling; Transpiration; Wettability
• ISSN: 1533-6808; 0887-8722; 1533-6808
• DOI: 10.2514/1.T6475

Motivated by knowledge gaps within the topics of wicking dry-out and graded porosity, we present a computational method to determine the optimum micropore distribution for maximum cooling in response to an incident heat flux on the leading edge (LE) of hypersonic aircraft. The investigated geometry is a 5° half-angle wedge with a semicircular nose tip of 1 mm radius of curvature. The aerodynamic heat flux along the LE is estimated for Mach 5–8. The complex method of optimization is a gradient-free method that is used to maximize the cooling effectiveness in the porous LE with stratified permeability. We show that porosity optimization leads to a modest 6% increase in cooling effectiveness near the stagnation point. The results are then used to analyze the LE’s ability to pump the liquid coolant passively from capillary action during acceleration. We determine that a porous LE having an average pore diameter of 190  μm with strong wettability performs far better than a pore diameter of 350  μm with poor wettability.