Additively manufactured porous geometries for hybrid turbine blade cooling

Traditional film cooling holes are limited by subtractive manufacturing techniques and experience depreciating performance when operating above critical velocity ratios. This study presents an alternative method of bringing coolant to the surface of the blade, via finite regions of porous material integrated throughout the blade, made possible by advances in additive manufacturing. Both experimental and computational studies were performed on the hybrid configuration to characterize downstream and off-wall performance. Downstream adiabatic effectiveness values of the hybrid configuration indicate similar performance to slots while providing better structural stability. Results from the hybrid configuration were also directly compared to film cooling holes, producing scenarios with equivalent spatially-averaged effectiveness while using 50% less coolant per unit width, and doubling spatially-averaged effectiveness values while requiring twice the coolant mass flow rate of film cooling. Finally, the RANS computational model accurately predicted downstream effectiveness values, at low velocity ratios, within experimental uncertainty.