Optimization Design And Characteristic Analysis Of Wind Turbine Blade Using NPU New Airfoil

Wind energy is a renewable energy resource. Due to the exhausting of the traditional energy resources and the worldwide appeal for sustainable development, wind energy is attracting more and more attention of the word, and the relative key technologies also become research hotspots of the worldwide scholars. The aerodynamic optimization design, loads calculation, inherent character and damage analysis are researched in this paper. The main contents of the paper are as follows.Based on the state 863 project, named"Design and experimental study of the advanced airfoil for wind turbine"(2007AA05Z448), the NPU-WA airfoil family were selected, which were designed by Northwest Polytechnical University. According to blade element- momentum theory (BEM), blade optimum theory and the aerodynamic characteristic of the NPU-WA airfoil family, a global optimum design method for Horizontal Axis Wind Turbines (HAWT) is presented. The method is set chord length, torsion angle as design variables, with the objective to satisfy the maximum annual energy output, using the Genetic Algorithm to carry on the global optimum searching. Using this method, a 1.5MW HAWT blade is designed. Besides, to account for tip loss, hub loss, cascade effects and the modified axial induction factor, the aerodynamic performance is accurate calculated. Compared with an existing 1.5MW wind turbine, the aerodynamic performance calculation results indicated that the performance of the designed wind turbine was better than that of the existing one, which verifies that the new designed airfoils have better aerodynamic performance.The load calculation is the foundation of blade structural analysis, blade loads significantly effect on the wind turbine stability. Based on the blade load analysis, the loads are calculated in steady wind farm and turbulence wind farm. Besides, different load cases are designed based on Standard IEC 61400-1, and the blade root ultimate loads are calculated.The iterative method is used for natural frequency calculation in last section. For the blade, the twist angle, rotating speed and pitch angle are taken into account to analyze the blade natural frequency. The vibration and elastic deformation blade happen easily with the effect of wind loads, aerodynamic damping plays a very important role. The blade damage malfunction is analyzed in dynamic damping. In this paper, through the research of the blade sections' aerodynamic damping characteristic, the blade tip aerodynamic damping model for wind turbines is set up. Taking the change of aerodynamic damping which produced in the process of braking active as the key point of the research, the aerodynamic damping of the blade tip brake shaft is calculated based on the aerodynamic damping model. Then, the time history of the blade tip deflection is calculated based on the structural dynamic equation of the blade tip. Consequently, whether the blade tip brake shaft is damageable can be confirmed.