Effects of grit roughness and pitch oscillations on the S815 airfoil

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Horizontal axis wind turbine rotors experience unsteady aerodynamics due to wind shear 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 calculation of rotor performance and loads. The rotors also experience performance degradation due to surface roughness. These surface irregularities are cause by the accumulation of insect debris, ice, and 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 ... continued below

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153 p.

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Reuss Ramsay, R.; Hoffman, M.J. & Gregorek, G.M. July 1, 1996.

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Description

Horizontal axis wind turbine rotors experience unsteady aerodynamics due to wind shear 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 calculation of rotor performance and loads. The rotors also experience performance degradation due to surface roughness. These surface irregularities are cause by the accumulation of insect debris, ice, and 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 be used to validate analytical computer codes. A S815 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 and stationary model conditions, as well as with the model undergoing pitch oscillations. To study the possible extent of performance loss due to surface roughness, a standard grit 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 used for steady state conditions were 0.75, 1, 1.25, and 1.4 million, while the angle of attack ranged from {minus}20{degree} to +40{degree}. With the model undergoing pitch oscillations, data were acquired at Reynolds numbers of 0.75, 1, 1.25, and 1.4 million, at frequencies of 0.6, 1.2, and 1.8 Hz. Two sine wave forcing functions were used; {+-}5.5{degree} and {+-}10{degree}, at mean angles of attack of 8{degree}, 14{degree}, and 20{degree}. For purposes herein, any reference to unsteady conditions means that the model was in pitch oscillation about the quarter chord.

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153 p.

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OSTI as DE96007942

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  • Other Information: PBD: Jul 1996

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  • Other: DE96007942
  • Report No.: NREL/TP--442-7820
  • Grant Number: AC36-83CH10093
  • DOI: 10.2172/266692 | External Link
  • Office of Scientific & Technical Information Report Number: 266692
  • Archival Resource Key: ark:/67531/metadc668527

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  • July 1, 1996

Added to The UNT Digital Library

  • June 29, 2015, 9:42 p.m.

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  • March 31, 2016, 8:54 p.m.

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Reuss Ramsay, R.; Hoffman, M.J. & Gregorek, G.M. Effects of grit roughness and pitch oscillations on the S815 airfoil, report, July 1, 1996; Golden, Colorado. (digital.library.unt.edu/ark:/67531/metadc668527/: accessed September 26, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.