Influence mechanism of local air film holes blockage on cooling efficiency of turbine blades

Abstract

In order to explore the cooling air film damage mechanism of aero-engine turbine blades in different blockage states, the air film cooling efficiency, outlet temperature and flow rate variations have been studied in three typical positions with different blockage ratios. The results show that the blockage of the air film holes decreases the air film cooling efficiency in the downstream region of the outlet boundary, and the decreasing amplitude increases non-linearly. When the temperature of the air film hole is lower than 1100 K, the cross-section of the air film gradually flattens out and the air film becomes thinner with the increase of the blocking ratio. When the blockage is in inlet position A, and B = 0.8, the influence on cooling efficiency of the air film performs most apparently. Moreover, when the cooling efficiency is near x/d = 1, the decreasing amplitude of efficiency reaches more than 7%. When the cooling efficiency is near x/d = 4, the decreasing amplitude of efficiency reaches more than 10%. In these two conditions, the effective protective air film area is the smallest, and the angle between the high temperature mainstream and the cooling fluid is the smallest, and the cooling fluid and the high temperature mainstream are the weakest in terms of resistance. Experiments on the effect of cooling fluid coverage of static blades have been conducted, and the results indicate that in the case of local air film holes blockage, the trend of damage degree of the cooling flow field is in good consistency with the analyzed results of the numerical model.