Discharge coefficient of turbine cooling holes: A review

Published information on the discharge coefficient of film cooling holes is classified in terms of the hole geometry, the external flow conditions at inlet and outlet, and the method of evaluation. This may be either theoretical or experimental. The information is reviewed primarily in the context of its use for evaluating discharge coefficients for conditions not directly covered by published data. It is shown that potential flow analyses can give acceptable accuracy for simple geometries with crossflows, while more complex cases require the use of correlated data, which may be incorporated in a range of predictive schemes. Deficiencies and inconsistencies in the published information are highlighted, and future developments are discussed.