| The early development of wind turbine industry in China is mainly distributed in the western regions with rich wind resources.However,as the regions with large power consumption are mainly concentrated in the central and eastern parts of China,and the problem of long-distance power transportation loss cannot be solved all the time,a large amount of power resources are wasted.Therefore,the development of wind power resources in China began to shift to the central and eastern regions with low wind speed,and the development of low-wind power projects has become one of the key directions of China’s wind power development.Low wind speed wind power projects can be divided into two types,one is complex terrain projects,the other is simple terrain projects.For low speed wind farms in complex terrain,they will face difficulties such as low cut wind speed and high turbulivity.Therefore,turbulivity has become an important parameter for the design and safe operation of wind power units in such areas.For the wind sensitive structure of the wind turbine blade,the force characteristics of the wind turbine blade in the presence of turbulence are very noteworthy problems.This experiment is designed on the basis of fully considering the real turbulent environment of the Huanghualiang Wind Farm in Zhangjiakou,Hebei.The aerodynamic performance of the NREL S810 airfoil under different turbulence degrees is studied,and the effect of turbulence on the aerodynamic performance of the airfoil is summarized.It provides a basis for the theoretical study of airfoil aerodynamic performance changes under different turbulence levels,and provides a reference for practical engineering applications.In this study,the wind tunnel test method was used to systematically study the effect of turbulence on the aerodynamic performance of the airfoil.The research content is as follows:(1)Considering the turbulivity at the hub height of the wind turbine in the actual complex mountainous terrain,the wind tunnel test regulating turbulivity methods are summarized and compared.In this paper,strip grid and mesh grid are set upstream of the model to change the turbulivity by adjusting the gap size of the grid.The maximum turbulence intensity achieved in the test is 13%.(2)Through the wind tunnel pressure test to study the large-scale wind turbine airfoil NREL S810,the airfoil aerodynamic coefficients under different turbulence degrees are obtained.With the increase of incoming flow turbulence,the lift coefficient and drag coefficient of airfoil both increase at first and then decrease.When the incoming flow turbulence Iu≥11.0%,the aerodynamic coefficients of airfoil are significantly lower than those of uniform flow.In addition,the stall delay becomes more and more obvious with the increase of incoming turbulence,and the stall Angle of attack continues to move backward.When the turbulence intensity increases to13.0%,there is no obvious stall Angle of attack within the range of the test Angle of attack.(3)The pressure coefficient of the airfoil surface under different turbulence degrees is analyzed,and it is found that as the turbulence degree increases,the minimum negative pressure value of the average wind pressure coefficient and the average wind pressure coefficient of the suction surface first decrease with the increase of turbulence degree.Increasing trend of change.As a result,the lift coefficient shows a trend of first increasing and then decreasing with the increase of turbulence.The boundary layer separation point of the airfoil gradually moved to the front edge with the increase of turbulence,but the boundary layer reattached again at a small angle of attack(α≤6°),while the boundary layer at a large angle of attack(α≥12°)With the increase of turbulence,the layer separation point first moved to the trailing edge and then to the front edge,resulting in a trend that the drag coefficient first increased and then decreased. |
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