Research On Aerodynamic Performance Optimization Of Vertical Axis Wind Turbine With Variable Pitch

Wind energy is a kind of clean energy with huge reserves and inexhaustible use.Wind turbine is a device that converts wind energy into mechanical energy.Its performance directly affects the utilization rate of wind energy.Vertical axis wind turbines can receive incoming flows from all directions without the need for a wind device.It has the advantages of uniform force,relatively low cost,low noise,and convenient installation and maintenance.However,it is difficult to operate at low wind speeds and has low efficiency.This problem hinders the further development of vertical axis wind turbines.Based on this,this paper designs a variable pitch mechanism to improve the aerodynamic performance of straight-bladed vertical axis wind turbines.Combined with the current research status of vertical axis wind turbines at home and abroad,this paper proposes an active variable pitch vertical axis wind turbine,which changes the pitch rule by changing the length of the push rod,and embeds the pitch rule through a user-defined function in Finite element simulation software,a numerical simulation of the wind-induced vertical axis wind turbine was carried out,and the aerodynamic performance of the 0° and-4° fixed pitch vertical axis wind turbine was compared,and the feasibility of the variable pitch mechanism was preliminarily verified.Since the active variable pitch vertical axis wind turbine needs to compile a complicated control program to control the blades to realize the pitch movement,and the built-in power supply and sensors and other modules increase the load and reduce the overall operating performance of the wind turbine.A passive variable pitch vertical axis wind turbine is proposed.First,the performance of the ±5° ～ ±30° symmetrical variable pitch amplitude wind turbine at wind speeds of 3m/s,6m/s and 9m/s has been studied.The results show that: The better,the combination of proper symmetrical pitch and proper wind speed conditions can effectively increase the torque of the blades in the upwind zone,optimize the overall angle of attack in the upper and lower wind zones,a nd maximize the performance of the wind turbine.Among them,the combination of 3m/s wind speed and±20° variable pitch amplitude fan is the best,and the best combination of 6m/s,9m/s wind speed and ±10° variable pitch amplitude fan;then by changing the length of the push rod to make the pitch amplitude no longer symmetrical,comparing the difference between the aerodynamic performance of the wind turbine,it is found that the change of the push rod can optimize the angle of attack in the downwind area,and the appropriate increase of the negative pitch area can increase the overall torque,thereby improving the energy capture of the wind turbine.Among them,the asymmetric pitch amplitude fan Run2 performed outstandingly at a wind speed of 3m/s,which increased the average wind energy utilization rate of the wind turbine by 19.22%,and the asymmetric pitch amplitude fan Run7 performed outstandingly at a wind speed of 6m/s,which increased the average wind energy utilization rate of the wind turbine by 14.07%.Finally,prototypes of Run2 and Run7 were made and compared with 0° and-4° fixedpitch fans.The experiment confirmed the superiority of the variable-pitch fan.The average power of the variable-pitch fan Run2 is 14 times of that of the 0° fixed-pitch fan.