Effect of Two-Head Flared Hole on Film Cooling Performance over a Flat Plate

Film cooling is commonly utilized in turbine blades to decrease the temperature of the air stream from the combustion chamber that contacts directly with the blades. The shape of a cylindrical hole (CH) with the geometrical variations at inlet and outlet ports was examined using the 3D Reynolds-averaged Navier–Stokes equations (RANS) with a shear stress transport (SST k − ω) turbulence model to study the effect of the two-head flared hole on film cooling effectiveness (FE) at high accuracy with a small y+ value. To assess the effect of the changes, each geometry of the hole was changed one after another while the other parameters were kept invariable at the test value (cylindrical hole). The numerical laterally averaged film cooling effectiveness (ηl) of the CH case was validated and compared to the experimental data. The simulation results with the two-head flared hole indicated that most of these shape changes increase the FE as compared to the CH case. In particular, the maximum spatially averaged film cooling effectiveness (ηs) with hole shape expanded along the flow direction at the outlet port reached 60.787% in comparison to the CH case.