Wind Turbine Blade Design And Flutter Analysis

The blade is one of the most important parts for wind turbine. Based on better designed blade, higher power coefficient is obtained and better economic profit can be gained. In this paper, a 600KW horizontal axis wind turbine is designed with Schmitz theory, and its aerodynamic performance is calculated and analyzed. Then, the paper presents two different models, stall controlled wind turbine and pitch controlled wind turbine, and corresponding control strategies. In the same working condition, their aerodynamic performances are compared. The result shows, for pitch controlled wind turbine rotor, higher power coefficient is obtained at low wind speed, output of power keep constant and the load of blade and drive train is significantly reduced at high wind speed. Especially for load reduction, it is most important to improve performance of wind turbine.Load of blade is more complicated. During wind turbine running, aerodynamic, elastic and inertia load are applied on blade. Furthermore, the structural characterizes of blade are long span, short chord and small stiffness. So flutter often occurs to the blade, which could cause blade damaged. In this dissertation, the blade of wind turbine is simplified as the cantilever beam. The motion differential equation of the airfoil is established and the formulation of aerodynamic stiffness and aerodynamic damping are obtained based on fluid-structure interaction when the blade occurs to bend-torsion coupled vibration. The paper also introduces the analysis method of the blade aerodynamic-elastic stability. Then, the blade aerodynamic-elastic stability is investigated by means of the analysis method, and effect of aerodynamic moment to blade stability is discussed. At last, motion trend of airfoil is obtained, by means of solving differential equation of airfoil with Runge-Kutta method, to validate the correctness and validity of the analysis method. The results are as follows: (1) The analysis method is correct and valid to analyze the blade aerodynamic-elastic stability. (2) The aerodynamic moment has significantly effect to blade aerodynamic-elastic stability, so it can not to be neglect.