Experimental and numerical investigation of transpiration cooling for sintered porous flat plates

The flow and heat transfer characteristics of transpiration cooling through sintered porous flat plates with particle diameters dp = 40 and 90 μm was investigated experimentally and numerically with dry air as the coolant stream. The effects of injection rate, solid matrix thermal conductivity and particle diameter on the external surface temperature distribution were investigated. The experimental results show that even a small amount of coolant injection notably reduces the heat transfer from the hot gases. The cooling effectiveness increased with increasing injection rate, with the increases becoming smaller as the gas injection rate was increased. The temperature and cooling effectiveness distributions along the transpiration surface exhibited slightly different tendencies for the four sintered porous walls due to the different thermal conductivities and the different particle diameters of the solid matrix. The temperature distribution on the porous bronze plate was more uniform than that on the sintered stainless steel plates. The cooling performance for the porous wall with the smaller particle diameters was better mainly due to the enhanced convection heat transfer inside the wall.