Wind tunnel tests of the FFA-W3-241, FFA-W3-301 and NACA 63-430 airfoils

This report deals with 2D measurements of the FFA-W3-241, FFA-W3-301 and NACA 63-430 airfoils. The aerodynamic properties were measured at Re = 1.6x10"6. The VELUX open jet wind tunnel with a background turbulence intensity of 1% was used. The airfoil sections had a chord of 0.60 m and a span of 1.9 m and end plates were used to minimize 3D flow effects.

The measurements comprised both static and dynamic inflow where dynamic inflow was obtained by pitching the airfoil in a harmonic motion. We tested the influence from vortex generators and leading edge roughness both individually and in combination. The aerodynamic characteristics were measured and the agreement between calculations and measurements was fair for FFA-W3-241 but not good for FFA-W3-301 and NACA 63-430.

In general calculations overestimated maximum C_L and sometimes underestimated minimum C_D. Maximum C_L for smooth flow was in good agreement with calculated maximum C_L for leading edge transition flow and this could serve as a worst case calculation. We determined the influence from vortex generators and they should always be applied on thick airfoils to increase maximum C_L.

We determined the influence from leading edge roughness, which reduced maximum C_L and increased minimum C_D. Compared with the NACA 63-4xx airfoils, the FFA-W3 airfoils were found better suited for the inboard part of a wind turbine blade both with and without vortex generators. (au).