Flow Characterization of Porous Ultra-High-Temperature Ceramics for Transpiration Cooling

Porous ultra-high-temperature ceramics (UHTCs) are a candidate group of materials for transpiration cooling hypersonic vehicles due to their exceptionally high melting point, typically above 3000 K. Their operating temperature permits higher amount radiative than that achievable with conventional materials, which reduces the required coolant mass flow rate cool surface. This work experimentally examines internal and external behavior porous UHTC made zirconium diboride purpose cooling. A dedicated ISO standard permeability test rig was built. The outflow velocity distribution acquired employing miniature hot-wire anemometry. data obtained pressure loss across samples agree Darcy–Forchheimer model in media; respective Darcy Forchheimer coefficients calculated reported. Cleaning surface using sandpaper or an ultrasonic bath raised coefficient by up 19%. maps exhibit good uniformity average deviation 25.1% respect mean value. Individual jets absent, varies within same order magnitude.