The leading-edge regions of turbine vanes and blades require careful attention to their cooling designs because of the high heat loads. External cooling is typically accomplished with dense “showerhead" arrangements in this area. Shaped holes have become prevalent in film cooling designs, and many studies investigate the performances on various designs on flat plates and even airfoil models. Very few published studies incorporating shaped hole designs in the showerhead have been performed, but among them is the indication that shaped holes may offer an improvement in coolant performance compared to cylindrical holes. Based on the physics inherent to the leading-edge region previously reported in the literature and seen in a RANS CFD simulation performed for this study, a shaped hole was designed with the goal of high performance in the showerhead. The performance and behavior of this shaped hole design was studied in comparison to a traditional cylindrical hole design in a series of experiments. The hole designs were built into the leading edge of a scaled-up turbine blade test model in a low-speed simulated linear cascade. To accomplish a more engine-representative test environment, a nominally 18% approach turbulence level was used for this study. Adiabatic effectiveness as a function of coolant injection rate was measured for the two designs using infrared thermography. In addition, off-the-wall thermal field measurements were performed for each hole geometry in the leading-edge region. These thermal fields were taken both in areas surrounding the showerhead and inside the breakout areas within the stagnation row.


Adiabatic Effectiveness and Thermal Field Measurements of a Shaped Hole in the Showerhead of a Model Turbine Blade

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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