Numerical study of transpiration cooling at different outlet angles and hole pattern

The effects of transpiration cooling depends on the distribution of micropores in porous materials. The work simplifies the porous medium to a micro-scale pore plate structure that is densely organized, based on the idea of the capillary bundle model. The effects of hole pattern and hole outlet angle on transpiration cooling are investigated using numerical simulation. It is discovered that the hole outlet angle mostly affects the homogeneity of temperature distribution and has minimal effect on the surface cooling efficiency. The temperature uniformity index dropped by 35.9% yet the surface cooling efficiency only declined by 1.1% when the outlet angle was lowered from 45° to −45°. Furthermore, the temperature uniformity and cooling efficiency are directly affected by the hole pattern. When the long axis of the elliptical hole is parallel to the mainstream, it can achieve the best temperature uniformity; however, when the long axis is perpendicular to the mainstream direction, it can achieve higher cooling efficiency. Third, the material’s permeability will be decreased to varying degrees depending on the hole pattern and hole outlet angle. The results have important reference significance for the design of porous materials used for transpiration cooling.