Aerodynamic Calculation And Structure Design Analysis Of Composite Wind Turbine Blades

In this paper,the material for wind turbine blades adopted is the glass fiber reinforced epoxy resin matrix composites. Based on a rated power output of 20 KW wind turbine, the paper designs the aerodynamic shape of the blades, analyzes aerodynamic performance of them and makes the analysis of structural design of them by establishing finite-element models and coupling the pressure on the blade. The details are as follows:This paper designs the aerodynamic shape of the blades by using the Wilson method and obtains shape parameters of different airfoil surfaces in the spanwise length. And then, the paper makes the geometric modeling of wind turbine by use of SOLIDWORKS.The blade geometry model is imported in Ansys Workbench to delimit flow field grids.And then, the paper, for the rated condition and 10 non-design conditions, chooses the CFX solver to do aerodynamic calculation for the blade model. After the end of the solution, for the model in the rated condition, this article makes the flow-field analysis in the CFX-Post. By observing the results, pressure distribution, streamline-speed distribution of different airfoil surfaces in the spanwise length and the mechanism of producing aerodynamic lift are analyzed. Besides, by using the results, it analyzes the aerodynamic performance of the models in all the 11 conditions, and finds the best of the tip-speed ratio should be around 7;but in reality it only reaches 3.6 under the rated condition and the corresponding power coefficient is just 0.294 which still has a large gap with the expected value of 0.3744. Thus, it proposes an improved proposal to provide a design basis for following aerodynamic design optimization of the wind turbine.This paper analyzes the load on blades and works out a preliminary lay-up scheme according to the ply-design specifications. And then, it uses Ansys ICEM to divide structural grids of the blades and establishes the finite-element models of them based on Ansys. By using pressure coupling technology, for two kinds of harsh working conditions, wind pressure is loaded to the nodes of the outer surface of the models respectively. Through static strength analysis, the lay-up scheme of skin and main girder structure is improved to meet the requirements of static strength. Besides, the paper analyzes the stability of blade structure.The results show that the structure under the two conditions both meet the requirements of stability.Finally, the modal analysis is done for the blade model in this paper. The results show that the first-order natural frequency of the blade is 2.6609, which is close to the excitation frequency 3.9 of the rated condition, so that the resonance occurs easily. Thus, the paper proposes a subsequent, structure reasonable design proposals: Through changing the partial or whole rigidity of the blades, the natural frequency is made far away from the rotary frequency of the wind turbine or the natural frequencies of other components in order to avoid the resonance.