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Civil Engineering Graduate Seminar

Xiao Sun
PhD Candidate
Civil and Environmental Engineering
Michigan Technological University

This study aims to design several types of aerodynamic control devices using smart material actuators to reduce the vibration of  wind turbine blades. The concepts of piezo stack actuator based smart external and internal flaps are proposed, including the basic flap layout, the operating range and the settings, etc. And the concept of ionic polymer metal composite based microflap is also proposed. In order to compensate the aerodynamic forces, centrifugal forces and gravitational forces acting on the flap under the wind turbine’s normal operational conditions, the required energy output from the actuators is calculated. To meet the energy requirements, the proper type, number and configuration of actuators are determined. Amplification systems are designed to enhance the displacement output at the expense of the force output. After designed the mechanical system, a generic flap control scheme is developed using the multiblade coordinate transformation, gain scheduling technique and proportional-integral-derivative controller. A series of aeroelastic-aerodynamic time marching simulations are performed on the NREL 5MW wind turbine with the proposed flap systems and control scheme to obtain the time response under the normal operational conditions. The time series data is analyzed from a fatigue perspective and the results show significant reductions in the vibration fluctuation and the damage equivalent loads in terms of the blade out-of-plane deflection and blade root flapwise bending moment.