The hypothesis, posed in Part I [1], that excessive endwall loss of high lift low pressure turbine (LPT) airfoils is due to the influence of high stagger angles on the endwall pressure distribution and not front-loading is evaluated in a linear cascade at Re = 100,000 using both experimental and computational studies. A nominally high lift and high stagger angle front-loaded profile (L2F) with aspect ratio 3.5 is contoured at the endwall to reduce the stagger angle while maintaining the front loading. The contouring process effectively generates a fillet at the endwall, so the resulting airfoil is referred to as L2F-EF (Endwall Fillet). Although referred to as a fillet, this profile contouring process is novel in that it is designed to isolate the effect of stagger angle on endwall loss. Total pressure loss measurements downstream of the blade row indicate that the use of the lower stagger angle at the endwall reduces mixed out mass averaged endwall and passage losses approximately 23% and 10% respectively. This is in good agreement with computational results used to design the contour which predict 18% and 7% loss reductions. The endwall flow field of the L2F and L2F-EF models is measured using stereoscopic particle image velocimetry (PIV) in the passage. These data are used to quantify changes in the endwall flow field due to the contouring. PIV results show that this loss reduction is characterized by reduced inlet boundary layer separation as well as a change in strength and location of the suction side horseshoe vortex (SHV) and passage vortex (PV). The endwall profile contouring also produces a reduction in all terms of the Reynolds stress tensor consistent with a decrease in deformation work and overall flow unsteadiness. These results confirm that the stagger angle has a significant effect on high-lift front-loaded LPT endwall loss. Low stagger profiling is successful in reducing endwall loss by limiting the development and migration of the low momentum fluid associated with the SHV and PV interaction.
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ASME Turbo Expo 2013: Turbine Technical Conference and Exposition
June 3–7, 2013
San Antonio, Texas, USA
Conference Sponsors:
- International Gas Turbine Institute
ISBN:
978-0-7918-5522-5
PROCEEDINGS PAPER
Endwall Loss Reduction of High Lift Low Pressure Turbine Airfoils Using Profile Contouring: Part II — Validation
Keith Sangston,
Keith Sangston
University of Arizona, Tucson, AZ
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Jesse Little,
Jesse Little
University of Arizona, Tucson, AZ
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M. Eric Lyall,
M. Eric Lyall
Air Force Research Laboratory, Wright-Patterson AFB, OH
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Rolf Sondergaard
Rolf Sondergaard
Air Force Research Laboratory, Wright-Patterson AFB, OH
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Keith Sangston
University of Arizona, Tucson, AZ
Jesse Little
University of Arizona, Tucson, AZ
M. Eric Lyall
Air Force Research Laboratory, Wright-Patterson AFB, OH
Rolf Sondergaard
Air Force Research Laboratory, Wright-Patterson AFB, OH
Paper No:
GT2013-95002, V06AT36A024; 11 pages
Published Online:
November 14, 2013
Citation
Sangston, K, Little, J, Lyall, ME, & Sondergaard, R. "Endwall Loss Reduction of High Lift Low Pressure Turbine Airfoils Using Profile Contouring: Part II — Validation." Proceedings of the ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. Volume 6A: Turbomachinery. San Antonio, Texas, USA. June 3–7, 2013. V06AT36A024. ASME. https://doi.org/10.1115/GT2013-95002
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