Abstract
Prediction of film cooling performance on turbine airfoils with multiple rows of film cooling holes based on the measured performance of a single row of holes relies on use of superposition analysis. There have been many past studies of superposition predictions of film cooling adiabatic effectiveness with similar hole shapes, either cylindrical or shaped holes. Recently there has also been a study proposing using a superposition technique to predict overall cooling effectiveness for multiple rows of film cooling holes. In this study, superposition predictions for adiabatic effectiveness and overall cooling effectiveness were evaluated for multiple rows of film cooling holes with varying hole geometries. The test configurations used mimicked the influence of upstream showerhead film cooling holes followed by either baseline 7-7-7 holes or an additively manufactured optimized film cooling hole which included external vortex generators that improved attachment of the coolant jets. Results showed the commonly used Sellers superposition model provided reasonable predictions of adiabatic effectiveness for the more standard 7-7-7 holes, but poor predictions for the optimized holes using vortex generators. Accuracy of the predictions of overall cooling effectiveness based on measured adiabatic effectiveness were found to be good.
