Experimental Investigation of Aerodynamic Devices for Wind Turbine Rotational Speed Control: Phase II

In light of the need to produce energy using more robust, reliable and efficient wind turbine designs, a range of new technologies has been explored. Trailing-edge aerodynamic devices represent one such technology that offers the potential for improved horizontal axis wind turbine performance. Indeed, these devices are particularly attractive for two reasons: to prevent turbine rotation speeds.from exceeding reasonable limits during high wind or loss of load situations, and for power modulation. Results from a previous investigation (Miller, 1 995) identified and evaluated the capabilities of five trailing-edge aerodynamic devices on a NACA 643-6 1 8 airfoil. The primary focus of the Phase I work was to enhance braking capabilities for wind turbines during overspeed situations. Powermodulation aspects were not specifically addressed. The aerodynamic capability of each Phase I device configuration was evaluated during low speed wind tunnel tests at Wichita State University (WSU). Phase 2 efforts, involving additional wind tunnel testing, were performed in an attempt to improve or optimize this particular configuration's performance and applicability for use on wind turbines.The impact of lip length, vent angle, pivot location and device chord were examined further. A significant amount of experimental data was gathered on lift, drag, quarter chord moment, and device hinge moment coefficients as a function of angle of attack and device deflection. This report documents the results of the Phase 2 investigation.