Effect of blockage configuration on film cooling with and without mist injection

Film cooling, as an effective protection technology, is widely applied in gas turbines to prevent components like vane blades from the hot mainstream. However, ash and other contaminants contained in the gas easily deposit on blade surfaces, which results in blockages inside the film holes and a reduction of the coverage area of the coolant air. Two blockage configurations (hemispherical and tetrahedral blockages) with a similar blockage ratio are analyzed in this study. In addition, mist injection with three droplet sizes (1 μm, 5 μm and 10 μm) is also considered. It is found that the position of the blockage configuration shows almost no influence on the cooling performance. In addition, the hemispherical blockage configuration results in a lower lateral film cooling effectiveness than the tetrahedral one. Finally, it is also concluded that the 5 μm droplet case shows more uniform distribution than other cases.