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| Modal analysis of umbrella wind turbine under different shrinkage angles |
| BAO Daorina*, WANG Xiaoxue, SHANG Wei, GUO Xiaodong, WANG Shuailong |
| College of Energy and Power Engineering, Inner Mongolia University of Technology, Hohhot, Inner Mongolia 010051, China |
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Abstract In order to truly reflect the vibration of umbrella wind turbines at different wind speeds and different shrinkage angles(0°,30°,45°,60°), the prestressed modal analysis of the 5kW umbrella wind turbine is carried out with the help of the Modal module in the ANSYS platform. Taking the aerodynamic force, centrifugal force and gravity as the boundary conditions, were the first six modality changes and the corresponding deformations of the umbrella wind turbine simulated and calculated. In the case of constant wind speed and constant revolving speed, the natural frequency of the first-order modality with the angle of contraction changes regulation is studied. The analysis results show that the relative difference between the natural frequency of the umbrella wind turbines and the operating frequency of wind turbines and the three times operating frequency of wind turbines are 57.2% and -90.5% respectively, which can completely avoid resonance and its design is reasonable.With the increase of the shrinkage angle, the natural frequency of the first-order decreases and the influence of the rotating speed on the natural frequency of the first order is greater than that of the wind speed. The shimmy is the main form of vibration in the low frequency region. The flapping and torsional vibrations are mostly in the high frequency region. The first six modes of the wind turbine change smoothly with the increase of the wind speed, but the increase rate with the increase of the rotational speed is ob-vious, and the centrifugal force ratio against aerodynamic forces has a greater impact on the dynamic frequency of wind turbines.
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Received: 10 March 2018
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