Aerodynamic Design And Finite Element Analysis For A Low Speed Blade Of Wind Turbine

Blade is one of the core components of wind turbine, which determines the performance and life of the wind turbine, as a whole and the parts. This thesis is devoted to the study of development for horizontal axis wind turbine blade which is used in the fourth type of wind zone in China based on several existing blades. In terms of statics, based on blade element momentum theory, blade of aerodynamic shape and structural problems are designed and analyzed at the simulation software as BLADE, ANSYS. In terms of dynamics, based on Hamilton’s principle, the model of a blade with small flap deflection and large flag deflection are established under the unsteady aerodynamic force, which are derived by using the Green Berg’expressions. According to the dynamics equations, the characteristic of flap motion of turbine blade is studied. The main works are as follows:1Requirements of the wind turbine blade are proposed to suit for the third or firth type of wind zone by research of Chinese wind turbine market and demand of situation. According to the objectives and requirements, the fan blade configuration parameters and data capture, the aerodynamic shape of the blade has been designed. Then the performance of aerodynamic and loads were calculated by utilizing simulation software BLADE. The results show that the aerodynamic performance of the blade we designed achieve the expected requirements and the ultimate load is lower than the domestic models and fit for rule of design.2This article analysis the strength and stiffness under extreme conditions of wind turbines by figure of stress-strain, figure of deformation, which are obtained with the help of BLADE. At the last, the physical model test has been made to examine the effective of the finite element method. The results show that the finite element method can be used to analyze the structure of the blade effectively, the strength and stiffness of the blade also suit for the design.3The nonlinear equation of flap vibration is established by considering the wind blade as a rotating Euler-Bernoulli beam base on the Hamilton’s principle. The equations contain two modal, the small flap deflection and the large one. The unsteady aerodynamic force acting on the blade is received by Green-Berg. By using the DQM and assumed method, the natural frequencies of flap are calculated according to these two models. Influences of the rotational speed and the pitch angle to vibration characteristics are discussed. The two method and vibration characteristics derived from the two models are compared. The result indicates that1) the natural frequencies of the flap vibration improve with the increase of speed both in the aerodynamic force and non-aerodynamic force.2)The frequencies are symmetric about zero pitch angle, and improve by decrease of the absolute value of pitch angle. The influence of pitch is small when the speed is low, while is big when the speed is high. The impact will become obvious in the modal of large.3) When the rotational speed or the deflection of angle is low, the result of two models is nearly the same. When the rotational speed or the deflection of angle is high, we must consider the impact of deflection and Aerodynamic force.