INFLUENCE OF FILM COOLING HOLES PARTIAL BLOCKAGE ON COOLING EFFECTIVENESS

To study the effect of blockage on the film cooling performance, film cooling plate models with cylindrical hole, compound hole, and fan-shaped hole under the all-round blockage, leading-edge blockage, and trailing-edge blockage were established respectively. The anti-blockage performance of three kinds of the hole was compared. The result shows that the cooling performance of cylindrical holes is the worst due to the appearance of counter-rotating vortex pair (CRVP) under blockage. The cooling effectiveness decreases with the increase of the blockage ratio. With the re-attachment effect, the cooling effectiveness of downstream increases by 11% on the contrary. The cooling effectiveness of the compound hole decreases obviously with the all-round and trailing-edge blockages, meanwhile, the peak cooling effectiveness and the coolant coverage area decrease. However, the cooling effectiveness increases by 15% when the leading-edge is blocked. For fan-shaped hole, the change of velocity gradient affects the development of the anti-CRVP, which disappears under the all-round blockage and reduces the cooling effectiveness greatly. The change of cooling performance of leading-edge and trailing-edge is very slight no more than 5%. In conclusion, the fan-shaped hole shows the best anti-blockage capability under the trailing-edge blockage condition and the all-round blockage condition with a high blow ratio, while the compound hole performs better in other conditions.