A study of flatback airfoils in dynamic motion

The use of flatback airfoils has been proposed for the inboard portion of horizontal axis wind turbine blades. The advantages of this blade geometry include a lighter, stronger blade with reduced sensitivity to soiling that is easier to transport. The DU97-W-300 and its 10% thick trailing edge flatback counterpart have been tested in a University of Wyoming wind tunnel in both static and dynamically pitching configurations because real wind turbine blades experience similar dynamic pitching due to yaw effects and shear in the inflow. Surface pressure and particle image velocimetry data have been collected at a Reynolds number of 121,000. The results show that the flatback does exhibit advantageous aerodynamic characteristics in both the static and dynamic configurations. Fundamental vortex shedding from the blunt trailing edge is present in both the static and dynamic cases, but in the more realistic dynamic case the flow is dominated by the effects of the dynamic pitching of the airfoil. This dynamic behavior has a severe impact on the aerodynamic characteristics of the blade. Better wind turbine blade designs would result from a more complete understanding of such realistic flow characteristics.