Two wind turbines dedicated airfoils tested in two different wind tunnels: Comparison and results

A brief comparison has been made between results of wind tunnel tests on airfoils DU 91-W2-250 and DU 93-W-210. The airfoils, with relative thickness of 25% and 21% respectively, have been designed by Delft University for stall controlled wind turbines. In the framework of the European Union JOULE program the two airfoils have been tested both in the Delft University and Torino University wind tunnel. The measurements in the two different facilities, with different sized models and different measurements technique have been compared at a Reynolds number of 1000000 in the angle of attack range from -45 to +45 degrees. In the paper only some examples from a large number of experimental results are presented. There are comparisons between Cl, Cd, Cm versus angle of attack for DU 93-W-210 and DU 91-W2-250, comparisons between pressure distributions and comparisons between complete 3D diagrams showing the difference of pressure distributions in the range from 0 to 20 degrees of the angle of attack. The comparisons of aerodynamic characteristics show good agreement for air-foil DU 91-W2-250 and some differences in stall and post stall data for DU 93-W-210.