| The vertical axis wind turbine has the advantages of no wind device,simple structure,easy maintenance,low noise and high safety.It can be divided into two types of lift and drag according to the different work mode of blade.The drag type vertical axis wind turbine has the advantages of high starting torque,low starting wind speed,but there is a low utilization rate and low speed wind energy problem.The lift type vertical axis wind turbine has the advantages of high speed and high utilization coefficient of wind energy,but there is also the problem of low starting speed at low wind speed.Lift-drag hybrid vertical axis wind turbine is a new type of wind turbine which has better starting performance and higher utilization rate of wind energy.At present,many scholars have carried on the thorough research to the vertical axis wind turbine's performance(the starting performance and the wind energy utilization rate)through the numerical computation and the wind tunnel experiment,and obtained certain research results.However,there is little research on the structure of vertical axis wind turbines.In order to make the vertical axis wind turbine widely used in our life,and to play its value,it is necessary to further study the overall structure of the wind turbine.In this paper,3 KW vertical shaft wind turbine with lift and drag is taken as the research object,and the following three parts are studied:(1)Structure design of wind turbine.According to the structure of the wind turbine,the wind turbine is divided into three parts:the wind wheel,the engine room and the tower.Firstly,through the analysis of the dynamic theory of wind turbine air,NACA0018 has been selected as the lift type blade,and then the chord length,wingspan,radius of gyration of the lift and drag type blades are designed and calculated.Based on the design results of aerodynamic parameters of the wind turbine,the structure,section selection and size parameters of the beam are designed,thus the design of the wind turbine part is completed.According to the structure and aerodynamic characteristics of the designed wind turbine,the disc type permanent magnet coreless generator and electromagnetic brake suitable for the small lift resistance composite vertical shaft wind turbine are selected.Then the structure of the main shaft is designed,and the type of the bearing is selected.The structural design of the engine room is completed on the basis of the design result before.The design of the tower plays an important role in the safe operation of the wind turbine.Through comparison and analysis of the merits and demerits of the steel,truss and steel tube towers,the steel tube structure tower is chosen as the 3KW lift-drag hybrid vertical axis wind turbine tower.(2)Static and dynamic analysis of main structure of wind turbine.First of all,the beam load of the blade shaft,the tower under rated condition are calculated using the finite element software of ANSYS finite element analysis of the wind turbine main structure design and calculation of the stress and displacement.On this basis,the strength and stiffness of the structure are checked and optimized.The modal analysis of the structure is carried out to calculate the low order natural frequencies and modes of the structure.The results show that the natural frequencies of the blade,spindle and tower are smaller than the first natural frequency.So the wind turbine will not resonate.The static and dynamic analysis of the main structure of the wind turbine ensures the safe and reliable operation of the wind turbine.(3)Make prototype and carry out field running test.Based on the results of theoretical analysis,we draw the blueprint and make all the parts of the wind turbine.Observing the idle running stability of the wind turbine in the field working environment,it is found that the wind turbine can start successfully at low wind speed of 2 m/s,and its starting performance is better.Under the wind speed of 13 m/s,there is no obvious deformation and vibration in the parts of the wind turbine.Based on the combination of analytical calculation and finite element analysis,the design and fabrication of lift-drag hybrid vertical axis wind turbine were carried out.The theoretical results are in good agreement with the actual experimental results.The design method meets the design requirements of the wind turbine,and provides reference for the design of the same type of wind turbine. |
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