Mechanical Analysis On Straight-blade Wind Turbines

With the over consumption of fossil energy and environmental issues, wind energy is paid more and more attention, each country is trying to develop it's own wind energy resources. Wind power generation in our country has been developed greatly in recent years, but our research on wind power generation is still far behind the advanced countries, especially the research on the blade. In this research, the straight blade used in vertical axis wind turbine is studied.The major research are as follows:1) It reviewed the research background of wind power generation, introduced the previous research on the vertical axis wind turbine, and expatiated the design theory of the aerodynamic load level on the vertical axis wind turbine, gave the model of the flow theory on the vertical axis wind turbine, analyzed the operating condition of the vertical axis wind turbine, derived formula the torque force that pushes against the wind wheel rotation, then used the formula to get briefly the torque that pushes against the wind wheel rotation.2) It analyzed the aerodynamic load level on the blade airfoil, mastered of the numerical research method of the airfoil aerodynamic load level; It investigated on the blade airfoil aerodynamic load level, then the research indicates that the airfoil has a good L/D and the aerodynamic load level; the FLUENT software is used to simulate the blade surface pressure, the results obtained here may provide some ideas for the blade aerodynamic load design.3) The flow field around the vertical axis wind turbine was obtained through establishing the computing model of vertical axis wind turbine three blades, it provided the foundation for further research and improving the design of the wind turbine.4) It made a detailed introduction to extract the wind pressure from FLUENT and convert to force suitable for the ANSYS through EXCEL and MATLB; based on the mechanics analysis of wind turbine blade in the two conditions, it shows that the blade had the maximum force at the connection point, so while designing the blade structure, it can focus on the blade connection point and it can reduce properly some mateirals at the less force such as at the tips; the natural frequency of the blade and vibration mode was got by analyzing its vibration characteristics; in this paper, one algorithm was studied on the fatigue life analysis of the blade, and an example was provided.5) The modal analysis and stability analysis were carrying out by establishing the finite element model of the tower. Through the modal analysis, its natural frequency was got, natural frequencies of each mode on the tower and the blade vary widely, resonance phenomenon did not occur. Through the stability analysis, buckling critical moment of the tower was given, the instability inclination of the tower was not great; also a suitable method for stability analysis of engineering applications was proposed.All above works done, the purpose is to find a new method of the wind turbine blades structural characteristics, then it can provide a new approach and reference for future wind turbine blade design and research. In the research, the conclusion on the blade research can be reference while designing the blade.