Effects of grit roughness and pitch oscillations on the S814 airfoil

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Horizontal-axis wind turbine rotors experience unsteady aerodynamics when the rotor is yawed, when rotor blades pass through the support tower wake, and when the wind is gusting. An understanding of this unsteady behavior is necessary to assist in the design of new rotor airfoils. The rotors also experience performance degradation due to surface roughness. These surface irregularities are due to the accumulation of insect debris, ice, and/or the aging process. Wind tunnel studies that examine both the steady and unsteady behavior of airfoils can help define pertinent flow phenomena, and the resultant data can also be used to validate analytical ... continued below

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153 p.

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Janiszewska, J.M.; Ramsay, R.R.; Hoffmann, M.J. & Gregorek, G.M. July 1, 1996.

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Description

Horizontal-axis wind turbine rotors experience unsteady aerodynamics when the rotor is yawed, when rotor blades pass through the support tower wake, and when the wind is gusting. An understanding of this unsteady behavior is necessary to assist in the design of new rotor airfoils. The rotors also experience performance degradation due to surface roughness. These surface irregularities are due to the accumulation of insect debris, ice, and/or the aging process. Wind tunnel studies that examine both the steady and unsteady behavior of airfoils can help define pertinent flow phenomena, and the resultant data can also be used to validate analytical computer codes. An S814 airfoil model was tested in The Ohio State University Aeronautical and Astronautical Research Laboratory (OSU/AARL) 3 X 5 subsonic wind tunnel (3 X 5) under steady flow with both stationary model conditions and pitch oscillations. To study the extent of performance loss due to surface roughness, a leading edge grit roughness pattern (LEGR) was used to simulate leading edge contamination. After baseline cases were completed, the LEGR was applied for both steady state and model pitch oscillation cases. The Reynolds numbers for steady state conditions were 0.75, 1, 1.25 and 1.5 million, while the angle of attack ranged from -20{degrees} to +40{degrees}. While the model underwent pitch oscillations, data were acquired at Reynolds numbers of 0.75, 1, 1.25, and 1.5 million, at frequencies of 0.6, 1.2, and 1.8 Hz. Two sine wave forcing functions {+-}5.5{degrees} and {+-}10{degrees}, were used; at mean angles of attack of 8{degrees}, 14{degrees}, and 20{degrees}. For purposes herein, any reference to unsteady conditions means the model was in pitch oscillation.

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153 p.

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OSTI as DE96007946

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  • Other Information: PBD: Jul 1996

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  • Other: DE96007946
  • Report No.: NREL/TP--442-8161
  • Grant Number: AC36-83CH10093
  • DOI: 10.2172/273772 | External Link
  • Office of Scientific & Technical Information Report Number: 273772
  • Archival Resource Key: ark:/67531/metadc672679

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Creation Date

  • July 1, 1996

Added to The UNT Digital Library

  • June 29, 2015, 9:42 p.m.

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  • March 28, 2016, 1:33 p.m.

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Janiszewska, J.M.; Ramsay, R.R.; Hoffmann, M.J. & Gregorek, G.M. Effects of grit roughness and pitch oscillations on the S814 airfoil, report, July 1, 1996; Golden, Colorado. (digital.library.unt.edu/ark:/67531/metadc672679/: accessed July 23, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.