Study On Influence Of Uncertain Airfoil Lift Drag Characteristics On Stochastic Aerodynamic Loads Of Wind Turbine

Wind turbine works in the complex and changeable atmospheric boundary layer all the year round.The wind speed and direction,turbulence and other factors are naturally of great randomness.The blade is the key component that determines the wind energy utilization efficiency of wind turbine.The design and manufacture process of turbine blade is very complicated,especially the geometric error of blade sectional airfoil has great uncertainty.Under the coupling effect of the random wind speed,turbulence,and uncertainty of blade airfoil geometric error,it is inevitable that the actual aerodynamic load of wind turbine deviates and fluctuates greatly compared with the theoretical design load,which affects the fatigue life and structural reliability of wind turbine.In this paper,the influence of uncertain aerodynamic characteristics of wind turbine airfoil was studied.The influence of random wind speed,turbulence intensity and geometric error of airfoil leading edge on the uncertainty of airfoil aerodynamic characteristics was quantified.The aerodynamic robust optimization design of airfoil under uncertain operating condition and geometric error was carried out,and the parametric model of airfoil lift drag uncertainty was established.The load uncertainty characteristics of wind turbine under typical conditions were obtained.The main contents of this paper are as follows:1.Study on the influence of uncertain lift drag characteristics of airfoil.Taking S809 airfoil as the research object,the influence of random wind speed on aerodynamic characteristics of airfoil was studied based on CFD numerical analysis method and non-embedded probability allocation point method.Based on the Kriging model and the interval analysis method,the effects of stochastic turbulence intensity and leading-edge geometric error on the aerodynamic uncertainty of airfoil were quantified.2.Robust optimization design of wind turbine airfoil.Based on the interval analysis and the Kriging model,the aerodynamic robust optimization design of wind airfoil under the conditions of stochastic turbulence and geometric leading-edge errors was carried out.The robust optimization,deterministic optimization and original airfoil were compared.The results show that the airfoil leading edge geometry changes obviously,and the sensitivity to uncertain factors is reduced by the proposed method.3.Study on the influence of uncertain lift drag characteristics of airfoil on aerodynamic load of wind turbine.Based on the uncertainty analysis of airfoil lift drag characteristics,the uncertain parameterized model of S809 airfoil lift-drag characteristics was established by integrating the effects of various uncertain factors.Taking NREL Phase Ⅵ wind turbine as the research object,based on the FAST aero-elastic theory,the time sequence spectrum of random load of wind turbine with uncertainty of airfoil lift-drag characteristics was calculated under different turbulence intensity conditions.Taking NREL Phase Ⅵ wind turbine as the research object,based on the FAST aero-elastic theory,the random load time sequence spectrum with uncertain airfoil lift drag characteristics under different turbulence intensity conditions was calculated.Based on the rain flow calculation method,the load sequence spectrum was transformed into the amplitude frequency distribution,and the equivalent fatigue load was obtained based on the load classification method,providing a reference for load analysis of wind turbine.4.Experimental study on the influence of random wind speed on load fluctuation of wind turbine.Based on the performance test platform of small wind turbines,the scaled NREL Phase Ⅵ wind turbine model was adopted to study the influence of the geometric profile change of airfoil leading edge on the load fluctuation of wind turbines under stochastic inflow wind speed,which provides a reference for airfoil design of wind turbine.