Study On The Aerodynamic Load Of Large Wind Turbines Based On Two Calculation Methods

Wind turbine is a towering structure that uses wind energy to generate electricity,the aerodynamic load is one of the main considerations for the design of wind turbine structure.Wind turbine winding has complex three-dimensional astyct characteristics,and the calculation method of the aerodynamic load of the wind turbine has its own limitations.Therefore,it is has academic value and engineering significance to compare the calculation method of the aerodynamic load of wind turbine,and to clarify its scope of application,characteristics and supplement the calculation method.Using the method of numerical simulation to study the interference effect of wind wheel rotation on the aerodynamic load on the surface of the wind turbine cylinder.Comparing the aerodynamic load results of large wind turbine blades obtained by Computational Fluid Dynamics(CFD)and Blade Element Momentum(BEM),analyzing the differences and reasons.Finally obtain the scope and characteristics of the two methods of calculation.The results show that:(1)The range affected by the aerodynamic load of the cylinder rotation is 0.2 to 0.7 times the diameter range of the wheel center,and the maximum impact is 0.5 to 0.6 times the diameter range of the wind wheel from the center of the hub.The reason for consideration is: the tail vortex of the wheel rotation affects the distribution of the aerodynamic load on the surface of the rear tower.(2)In the interval where the wind wheel rotation interferes with the aerodynamic load on the surface of the cylinder,the wind wheel rotation increases the maximum positive pressure of the cylinder wind face by about 150%,and the negative pressure maximum of the side wind surface increases by about 100%,and also narrows the wake flow.So it's not right to just use the tower as a towering building to calculate the surface aerodynamic load.(3)Based on the CFD and BEM calculation methods to obtain the blade root aerodynamic load,it is the same with the change of wind speed.But the values are different: This difference gradually increases as the wind speed increases,and the maximum difference is about 8% as it continues to increase to the rated wind speed.(4)Based on the CFD and BEM calculation methods to obtain the blade root aerodynamic load,it is the same with the change of the tip speed ratio.But the values are different: With the increase of tip speed ratio,the ratio of the difference value to the CFD method calculates the value is smaller and larger,and the ratio of the difference value to the CFD method calculation value is the smallest in the vicinity of the optimal tip speed ratio.(5)The BEM method makes a large correction to the axial thrust coefficient,so that the axial thrust value is larger than the calculation of the CFD method;Moreover,it does not take into account the effect of the Reynolds number effect on the wing lift ratio.The swing bending moment is larger than the calculation of the CFD method.Taking into account the computational efficiency,small wind turbines that are less affected by the Reynolds number effect may consider using the BEM method to calculate the aerodynamic load.Larger wind turbines should consider using the CFD method to calculate the aerodynamic load.