1 Risø National Laboratory for Sustainable Energy, Technical University of Denmark2 Department of Wind Energy, Technical University of Denmark
This report contains 2D measurements of the Risø-B1-18 and Risø-B1-24 airfoils. The aerodynamic properties were derived from pressure measurements on the airfoil surface and in the wake. The measurements were conducted in the VELUX open jet wind tunnel,which has a background turbulence intensity of 1%, and an inlet flow velocity of 42 m/s. The airfoil sections had a chord of 0.600 m giving a Reynolds number of 1.6×106. The span was 1.9 m and end plates were used to minimize 3D flow effects. Themeasurements comprised both static and dynamic inflow. Static inflow covered angles of attack from –5o to 30o. Dynamic inflow was obtained by pitching the airfoil in a harmonic motion around various mean angles of attack. The test matrix involved smoothflow, various kinds of leading edge roughness, stall strips, vortex generators and Gurney flaps in different combinations. The quality of the measurements was good and the agreement between measurements and numerical CFD predictions with EllipSys2D wasgood. For both airfoils predictions with turbulent flow captured very well the shapes of lift and drag curves as well as the magnitude of maximum lift. Measurements of Risø-B1-18 showed that the maximum lift coefficient was 1.64 at an angle of attack ofapproximately 13o. The airfoil was not very sensitive to leading edge roughness despite its high maximum lift. Measurements with stall strips showed that stall strips could control the level of maximum lift. The Risø-B1-24 measurements showed that themaximum lift coefficient was 1.62 at an angle of attack of approximately 14o. The airfoil was only little sensitive to leading edge roughness despite its high relative thickness and high maximum lift. Measurements with delta wing shaped vortex generatorsincreased the maximum lift coefficient to 2.02 and measurements with Gurney flaps increased the maximum lift coefficient to 1.85. Measurements with combination of vortex generators and Gurney flaps showed a maximum increase in the maximum lift coefficientto 2.17. At the design Reynolds number of 6×106 numerical predictions showed that there was a clear increase in the maximum lift coefficient of 0.22 for Risø-B1-18 and 0.21 for Risø-B1-24.