An experimental investigation on transpiration cooling with phase change subjected to non-uniform flame

Transpiration cooling with phase change is promising for thermal protection of scramjet engine due to the combined advantages of latent heat absorption of coolant and thermal insulation of gas film. Previous investigations primarily focused on the transpiration cooling subjected to uniform incoming flow. However, few investigations have revealed the effect of the non-uniformity of high-temperature flame on transpiration cooling with phase change. Moreover, the effect of porosity on transpiration cooling performance was seldomly mentioned. Herein, we experimentally investigate the transpiration cooling in porous media of alloy (Inconel 600) with deionized water as the coolant subjected to the non-uniform high-temperature flame. Moreover, the effects of porosity and type of transpiration material on cooling are investigated. Results show that when the injection rate is less than 16 %, local overheating occurs on the surface of the porous materials. The overheating phenomenon occurs earlier at lower injection rates. Moreover, the decrease in porosity of the transpiration material will lead to increases of the surface temperature and top/back surface temperature difference, as well as decreases of top-surface temperature non-uniformity and cooling efficiency. In addition, for the different porous materials with similar thermal conductivity, the specific surface area exhibits a dominant factor in transpiration cooling.