Angle of attack Alternating current Model chord length Drag coefficient Minimum drag coefficient Pressure drag coefficient Wake drag coefficient Uncorrected drag coefficient Lift coefficient Maximum lift coefficient Lift coefficient at angle of maximum lift, but with angle of attack decreasing Uncorrected lift coefficient Pitching moment coefficient about the quarter chord Pitching moment coefficient at angle of maximum lift, but with angle of attack decreasing Pitching moment coefficient at angle of maximum lift, but with angle of attack increasing Pitching moment coefficient about the quarter chord, at zero lift Uncorrected pitching moment coefficient about the quarter chord Pressure coefficient, @pm)/qm Minimum pressure coefficient Frequency Wind tunnel test section height Horsepower Hertz Grit particle size Grit particle size divided by airfoil model chord length Pressure Dynamic pressure Uncorrected dynamic pressure Dynamic pressure through the model wake Free stream dynamic pressure Reynolds number Uncorrected Reynolds number Time Corrected free stream velocity Velocity Uncorrected velocity Axis parallel to model reference line Axis perpendicular to model reference line ix Angle of attack Decreasing angle of attack Increasing angle of attack Median angle of attack Mean angle of attack Uncorrected angle of attack Tunnel solid wall correction scalar Solid blockage correction scalar Wake blockage correction scalar Body-shape factor 3.1416 Tunnel solid wall correction parameter Reduced frequency, nfclU, X 14. SUBJECT TERMS 15. NUMBER OF PAGES wind energy; horizontal-axis wind turbine; wind tunnel test data; wind turbine airfoil 16. PRICE CODE 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT

This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof.

This report was prepared as an account of work sponsored by an agency of the United States government.

Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. Foreword Airfoils for wind turbines have been selected by comparing data from different wind tunnels, tested under different conditions, making it difficult to make accurate comparisons. Most wind tunnel data sets do not contain airfoil performance in stall commonly experienced by turbines operating in the field. Wind turbines commonly experience extreme roughness for which there is very little data. Finally, recent tests have shown that dynamic stall is a common occurrence for most wind turbines operating in yawed, stall or turbulent conditions. Very little dynamic stall data exists for the airfoils of interest to a wind turbine designer. In summary, very little airfoil performance data exists which is appropriate for wind turbine design. Recognizing the need for a wind turbine airfoil performance data base, the National Renewable Energy Laboratory (NREL), funded by the U.S. Department of Energy, awarded a contract to Ohio State University (OSU) to conduct a wind tunnel test program. Under this program, OSU tested a series of popular wind turbine airfoils. A standard test matrix was developed to assure that each airfoil was tested under the same conditions. The test matrix was developed in partnership with industry and is intended to include all of the operating conditions experienced by wind turbines. These conditions include airfoil performance at high angles of attack, rough leading edge (bug simulation), steady and unsteady angles of attack. Special care has' been taken to report as much of the test conditions and raw data as practical so that designers can make their own comparisons and focus on details of the data relevant to their design goals. Some of the airfoil coordinates are proprietary to NREL or an industry partner. To protect the information which defines the exact shape of the airfoil, the coordinates have not been included in the report. Instructions on how to obtain these Coordinates may be obtained by contacting C.P. (Sandy) Butterfield at NREL.

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