Experimental investigation of airfoil models for use on wind turbine blades

In a continuing effort to provide experimental data for wind turbine airfoils, tests were conducted at the Ohio State University, Aeronautical and Astronautical Research Laboratory in the 3 X 5 subsonic wind tunnel on the National Renewable Energy Laboratory S814, S812, and S810 airfoil sections. The airfoils were tested for steady state and for model oscillating conditions having a test matrix which included Reynolds numbers of 0.75 through 1.5 million; however, for brevity, only the results for 1 million Reynolds number are included. The unsteady data discussed includes {plus_minus}10{degrees} sinusoidal angle of attack oscillation at 0.6 and 1.8 Hz at mean angles of attack of 8{degrees}, 14{degrees}, and 20{degrees}. In addition, the effect of the application of leading edge grit roughness was studied. In general, application of leading edge grit roughness reduced the maximum lift coefficient and zero lift pitching moment coefficient and increased the minimum drag coefficient for the steady state data. For the unsteady cases, there were increases in the maximum lift and pitching moment coefficient performance for all cases in comparison to the steady state data and a hysteresis behavior due to the oscillating motion.