Study On The Influence Of Operating Parameters On Aerodynamic Performance And Wake Of Vertical Axis Wind Turbine

As a kind of clean energy,wind energy is used as an effective source to meet the growing demand for energy and consume fossil fuels,which is renewable and pollution-free.Among them,vertical axis wind turbines（VAWT）have proven to be suitable for changing wind conditions,especially in urban environments,vertical axis wind turbines are widely used.Operating parameters,incoming flow conditions and wind turbine wake state are all important conditions affecting the performance of vertical axis wind turbines,so in order to obtain better aerodynamic performance and higher wind energy utilization rate of vertical axis wind turbines,it is necessary to study the operating parameters of VAWT itself,external flow conditions,and evaluate the influence of wake between different wind turbines to obtain the best installation position.In this paper,the lifting vertical axis wind turbine is taken as the research object,and the CFD numerical simulation method and theory are used to study the influence of operating parameters on VAWT aerodynamic performance,the influence of flow conditions on VAWT aerodynamic performance,and the influence of downstream arrangement of wind turbines on VAWT wake.The results show that the operating conditions of the vertical axis wind turbine will have a great impact on the aerodynamic performance of the vertical axis wind turbine.Among them,the blade tip speed ratio has the greatest influence on the aerodynamic performance of the vertical axis wind turbine,and each wind speed has its corresponding optimal tip speed ratio.However,the Reynolds number has little effect on the angle of attack and lift drag coefficient of vertical axis wind turbine operation,but the influence on the attack angle and lift drag coefficient of downstream blades is higher than that of upstream blades,and with the increase of Reynolds number,C_l and C_lmax can be effectively increased while reducing C_d,effectively delaying the occurrence of stall separation phenomenon.The turbulence intensity has a great influence on the aerodynamic performance of the vertical axis wind turbine,and increasing the turbulence intensity will significantly reduce the fluctuation of tangential load and normal load.Different flow conditions in the urban environment will have different effects on the aerodynamic performance of the vertical axis wind turbine,and the torque fluctuation on the vertical axis wind turbine blade will increase under gust conditions,which is easy to cause damage to the fan;Under oblique flow conditions,the small high diameter ratio will improve the aerodynamic performance of the vertical axis wind turbine.When the distribution position of two parallel vertical axis wind turbines is different,the aerodynamic performance of the wind wheel in the wake is completely different.When the two parallel vertical axis wind turbines are distributed in different positions,the aerodynamic performance of the wind wheel in the wake is completely different,when the downstream wind wheel and the upstream wind wheel are arranged in parallel,the aerodynamic performance of the downstream wind wheel is significantly reduced,and when the downstream wind wheel and the upper in the transverse position are staggered by a certain distance,the aerodynamic performance of the downstream wind wheel is significantly improved,and the aerodynamic performance of the downstream wind wheel is the best when the lateral distance is 1DWhen the two parallel vertical axis wind turbines are distributed in different positions,the aerodynamic performance of the wind wheel in the wake is completely different,when the downstream wind wheel and the upstream wind wheel are arranged in parallel,the aerodynamic performance of the downstream wind wheel is significantly reduced,and when the downstream wind wheel and the upper in the transverse position are staggered by a certain distance,the aerodynamic performance of the downstream wind wheel is significantly improved,and the aerodynamic performance of the downstream wind wheel is the best when the lateral distance is 1D.The operating parameters have a great influence on the wake of the vertical axis wind turbine.The influence of blade tip velocity ratio on the wake of vertical axis wind turbine increases with the increase of blade tip speed ratio,the loss of velocity in the wake also increases,and the vortex strength of the blade falling off at low blade tip speed ratio is large,and the fluctuation with azimuth is large.At high blade tip velocity ratios,airflow on the airfoil surface is relatively stable,resulting in less intensity of vortex shedding on the blade surface.The Reynolds number has little effect on the wake of the vertical axis wind turbine,but it has a great effect on the strength of the shedding vortex,and with the increase of the Reynolds number,the intensity of the vortex shedding on the blade surface becomes greater.Turbulence intensity has a great effect on the wake at low blade tip velocity ratio,but turbulence intensity has little effect on the wake of vertical axis wind turbines at high blade tip velocity ratio.Wind wheels arranged in different positions upstream and downstream have a great impact on the wake when the wind wheel rotates in different directions,and the speed of the wake between the two wind wheels will be increased when the wind wheel rotates in opposite directions.This paper studies the influence of operating parameters on VAWT aerodynamic performance,the influence of flow conditions on VAWT aerodynamic performance,and the influence of downstream arrangement of wind turbines on VAWT wake,so as to provide reference for the application conditions of vertical axis wind turbines in cities.