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.  Little dynamic stall data exists for the airfoils of interest to a wind turbine designer.  In summary, very little airfoil performance data exits 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 included 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.