Detailed velocity measurements were made along a flat plate subject to the same dimensionless pressure gradient as the suction side of a modern low-pressure turbine airfoil. Reynolds numbers based on wetted plate length and nominal exit velocity were varied from 50, 000 to 300, 000, covering cruise to takeoff conditions. Low and high inlet free-stream turbulence intensities (0.2% and 7%) were set using passive grids. The location of boundary-layer separation does not depend strongly on the free-stream turbulence level or Reynolds number, as long as the boundary layer remains non-turbulent prior to separation. Strong acceleration prevents transition on the upstream part of the plate in all cases. Both free-stream turbulence and Reynolds number have strong effects on transition in the adverse pressure gradient region. Under low free-stream turbulence conditions transition is induced by instability waves in the shear layer of the separation bubble. Reattachment generally occurs at the transition start. At Re = 50, 000 the separation bubble does not close before the trailing edge of the modeled airfoil. At higher Re, transition moves upstream, and the boundary layer reattaches. With high free-stream turbulence levels, transition appears to occur in a bypass mode, similar to that in attached boundary layers. Transition moves upstream, resulting in shorter separation regions. At Re above 200,000, transition begins before separation. Mean velocity, turbulence and intermittency profiles are presented.
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ASME Turbo Expo 2000: Power for Land, Sea, and Air
May 8–11, 2000
Munich, Germany
Conference Sponsors:
- International Gas Turbine Institute
ISBN:
978-0-7918-7856-9
PROCEEDINGS PAPER
Measurements in Separated and Transitional Boundary Layers Under Low-Pressure Turbine Airfoil Conditions
Ralph J. Volino,
Ralph J. Volino
United States Naval Academy, Annapolis, MD
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Lennart S. Hultgren
Lennart S. Hultgren
National Aeronautics and Space Administration, Glenn Research Center at Lewis Field, Cleveland, OH
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Ralph J. Volino
United States Naval Academy, Annapolis, MD
Lennart S. Hultgren
National Aeronautics and Space Administration, Glenn Research Center at Lewis Field, Cleveland, OH
Paper No:
2000-GT-0260, V003T01A065; 13 pages
Published Online:
August 4, 2014
Citation
Volino, RJ, & Hultgren, LS. "Measurements in Separated and Transitional Boundary Layers Under Low-Pressure Turbine Airfoil Conditions." Proceedings of the ASME Turbo Expo 2000: Power for Land, Sea, and Air. Volume 3: Heat Transfer; Electric Power; Industrial and Cogeneration. Munich, Germany. May 8–11, 2000. V003T01A065. ASME. https://doi.org/10.1115/2000-GT-0260
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