Numerical Analysis of Film Cooling Due to Simple/Compound Angle Hole Combination

Abstract

Film cooling technique is one of the gas turbine components saving from thermal failure. This article presents a numerical study of film cooling effectiveness due to two rows of simple and compound angle holes. The holes are inclined with 30° on a flat surface for all studied cases. Two orientation angles of the film cooling holes are applied (0° and 30°). Six cases are used to represent different configurations for the two rows. Three different values of velocity ratios (namely 0.5, 1.0 and 2.0) are represented during this study. The numerical model is validated through comparing the results of single row with simple holes with the available experimental works in the literature. As an interesting observation, it is found that the staggered arrangement provides better film cooling effectiveness than the in-line one for zero orientation angle configurations, while the in-line arrangement represents the highest effectiveness if all holes in the two rows have 30° orientation angle. The enhancement ratio of overall effectiveness corresponding to averaged film cooling has been calculated. The maximum enhancement ratio has been achieved with compound/compound in-line configuration with about 336.5% at velocity ratio equal 2. Using compound angle holes enhances the film cooling effectiveness with inline arrangement, while using it with staggered arrangement reduces the overall averaged film cooling effectiveness, especially at high velocity ratio.