Cooling performance and flow-field analysis of a hybrid scheme with different outlet configurations

Film cooling performance and flow-field of a hybrid scheme with different outlet configurations and circular film hole are investigated numerically in the present study. The hybrid scheme includes two consecutive film hole shapes with interior bending. The cylindrical film hole and the hybrid scheme with five different outlet configurations namely: trapezoid, elliptical with compound angle of 0° and 90°, rectangle and square are analyzed at blowing ratio of 0.5 and 1.0 and a density ratio of 0.94. The results conducted that the hybrid scheme provides less boundary layer thickness over the downstream surface as the injection flow remains attached to the downstream surface. In addition, increasing the hybrid scheme exit area leads to reduce the secondary flow jet penetration into the main flow due to a reduction in momentum flux ratio. Consequently, the hybrid square scheme enhances centerline and spanwise film cooling effectiveness at high blowing ratio. Additionally, the hybrid square scheme provides the highest overall area-averaged film cooling effectiveness at high blowing ratio among other cases studied. Furthermore, the hybrid square and trapezoid schemes provide the lowest pressure coefficient among other studied schemes. Owing to increase the injection flow velocity over the downstream surface, the hybrid scheme provides higher Nusselt number compared to the circular film hole and the hybrid scheme with square configuration provides the lowest Nusselt number among other hybrid scheme outlet shapes. esult, the hybrid square and trapezoid schemes are able to protect the airfoil surface at lesser coolant flow rate and aerodynamic losses, thus it has capability to increase the overall gas turbine efficiency with long-term gas turbine durability and reliability.