| Blade is the most important component in wind turbine. As the wind turbine becomes larger, megawatt wind turbine blade needs a higher standard in reliability and cost control.Usually, the traditional design method of wind turbine blade is to separate structure design from aerodynamic design. Because this traditional way wants to maximize the effective utilization of wind energy, and makes the whole frame big, thus leads to a higher cost in producing wind energy. On the other hand, with the development of new materials and the manufacturing technology of new materials, the traditional safety factor method may be conservative or not safe. Based on the design mathod of Reliability Based Multidisciplinary Design Optimization (RBMDO), this article puts forward that both aerodynamic performance and structure strength should be synthetically considered, in order to ensure the reliability and decrease the cost of wind energy as well. The main achievements of this article are as follows:(1) Optimization the aerodynamic shape of blade based on the aerodynamic performance. First, design the basic parameters, including the tip speed ratio, airfoil with aerodynamic data, and so on. Then optimization the chord and twist angle based on Blade Element Momentum theory (BEM), The rated power of wind turbine reachs2.65MW.(2) Optimization structure of blade based on the structural strength. First, choose the structure style and materials for the blade. Then, based on the method of safety factor optimize the thickness of0°glass fiber reinforced materials through build up an optimization model. The results just correspond to reality in both the thickness and mass distribution of wind turbine blade, and the tip deflection is less then the allowable value.(3) Based on the First Order Reliability Method, the method of reliability analysis has been studied, the method of reliability analysis in bending stress of wind turbine blade has been established, and the influence degree on reliability from material performance has been explored. Finally, the result that variation coefficient of material strength has the biggest influence on the reliability and the elastic model of the material places the second has been found. Based on all these findings, the reliability design model of wind turbine blade and optimizing the0°glass fiber reinforced materials can be established. The result of this design corresponds to the result of the design, which bases on the factor of safety method.(4) Based on XFOIL airfoil aerodynamic analysis software and BEM theory, the model of calculation the relative thickness of the airfoil has been set up, and this make the preparation for making the model of RBMDO. (5) Studying about the coupling relationship between aerodynamic performance of wind turbine blade and its quality, the conclusion that the rated power of the inboard blade airfoil first increases with the relative thickness and then decreases, when25%of the wingspan of the relative thickness of the airfoil at0.246, the rated power reaches to the maximum, as the relative thickness of airfoil becomes bigger, the weight of blade decreases, has been found.(6) Based respectively on maximum of the efficiency of wind energy, minimum the cost of wind energy efficiency, minimum the weigh of blade, the design model of RBMDO of the relative thickness of the airfoil blade and0°glass fiber reinforced materials are established. The optimization results show that the appropriate sacrifice of the wing energy utilization efficiency of wind turbine blade can significantly reduce the weigh of the blade, thereby reducing the cost of wind energy. |
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