An experimental investigation on phase-change transpiration cooling with SiC porous ceramic

Abstract

Transpiration cooling with phase change is an effective cooling method for protecting the leading edge of hypersonic vehicles and scramjet engines from thermal failure. Previous research has revealed the transpiration cooling performance with porous metallic materials or ceramic-based composites. However, limited research has explored how non-uniformity of heat fluxes of incoming flow affect phase-change transpiration cooling performance in sintered SiC particles. Herein, we experimentally investigate the transpiration cooling performance of sintered SiC porous plate subjected to high-temperature flame with non-uniform heat fluxes along the radial direction, and compare that to porous sintered metal particles. Results show that at 17 % coolant injection rate, overheating phenomenon is first observed at the center of stainless-steel porous plate due to the highest aerodynamic heat. Comparatively, the highest temperature at the center of the SiC porous plate (ε = 38.4 %) is capable of stabilizing at around 103 ℃ due to its higher thermal conductivity. Moreover, when oxygen-fuel ratio is lower (O/F = 0.86) and the coolant mass flow rate ${\dot{m}}_c$ is 4 mL/min, the SiC porous plate exhibits higher top-surface temperatures along with greater radial and longitudinal temperature gradients (7.9 ℃ and 78.1 ℃). Furthermore, when ${\dot{m}}_c$ is 3 mL/min, the top-surface center temperature oscillates with an average period of around 100 s and an amplitude of 861.3 ℃. Additionally, when the porosity decreases from 43.3 % to 38.4 %, the delayed oscillation onset, shortened periods, and increased temperature amplitude are obtained, at the cost of increase of inlet pressure, with a maximum pressure reaching up to 75.4 kPa.