Study On Shape Optimization Of Twin Vertical Axis Wind Turbine Based On CFD

Wind energy,as one of the most industrialized new energy sources,has attracted more and more attention in recent years,among which wind power is most commonly used to generate electricity by wind turbines.The traditional horizontal axis wind turbine(HAWT)has complex structure,difficult installation and high requirement for wind quality.It is very difficult to make a big breakthrough in technology.But the vertical axis wind turbine(VAWT)can overcome the above difficulties and adapt to the harsh wind environment better.Despite the advantages of vertical axis wind turbines in harsh weather,due to the complexity of their internal flow field,the research on vertical axis wind turbines in recent decades is relatively late and few,so there are still many deficiencies in its aerodynamics research.Because the problem of low wind energy utilization ratio of vertical axis wind turbine has not been solved well,the design of twin vertical axis wind turbine is proposed in this paper,which can effectively improve the wind energy utilization ratio of vertical axis wind turbine.In this paper,three-dimensional CFD numerical simulation method is used to solve the aerodynamic performance of H-type vertical axis wind turbine.All computational domains of this method are divided into structured grids.The flow field of wind turbine is solved by using the solver of STAR-CCM+ commercial software.The reliability of this method is verified by comparing with experimental data.Variable parameter method is used to study the aerodynamic performance and flow field variation of single-rotor vertical-axis wind turbine during its operation.The influence rules of wind speed,installation angle and blade number on single-rotor wind turbine are obtained,which can provide reference for improving the aerodynamic performance of vertical-axis wind turbine.Considering the problem of low wind energy utilization ratio of vertical axis wind turbine,a new design concept of twin vertical axis wind turbine is adopted to improve the wind energy utilization ratio of wind turbine.The influence mechanism of different parameters on the aerodynamic performance of twin wind turbine is studied by CFD numerical simulation method.The influence rules of the parameters such as the spacing between the rotors,installation angle and blade number on the wind energy utilization ratio of wind turbine is obtained.The results show that the smaller the clearance ratio of the twin vertical-axis wind turbine is,the more the wind energy utilization ratio is increased.Under the minimum clearance ratio calculated in this paper,the wind energy utilization ratio of the wind turbine is increased by 13.4%,while the phase difference and different wind directions of the two wind turbines have little effect on the aerodynamic performance of the twin wind turbine;the optimal installation angle of the twin vertical axis wind turbine is the same as that of the single-rotor vertical-axis wind turbine.With the increase of installation angle,the optimal wind energy utilization ratio increases first and then decreases;the chord length of blades and the number of blades,i.e.the solidity of the wind wheel,also affect the performance of the wind turbine.With the increase of solidity,the optimal tip speed ratio of the twin wind turbine decreases;the wind energy utilization ratio of the twin wind turbine is larger than that of the single-rotor wind turbine in each blade number,and the more blades,the wind turbine is sensitive to the spacing.That is to say,when the clearance ratio is reduced,the wind energy utilization ratio of the twin wind turbine with more blades increases more obviously.The aerodynamic characteristics of the above twin vertical-axis wind turbine can provide ideas for the shape optimization of the vertical-axis wind turbine.