Wind Tunnel Experimental Investigation And Numerical Simulation Of An Oscillating Airfoil Of Wind Turbine

The pitch and flap deformation on the blades will have an influence on the performance and structural reliability of the large wind turbine in actual situation.As the basic study on the factors affecting the performance of wind turbine,a series of experimental investigations of steady and pitching oscillating airfoil(NACA64418),which are often used on the top of large horizontal axis wind turbine blades,were down in a subsonic wind tunnel with pressure transducers and 2D PIV(Particle Image Velocimetry)system.Compare the differences of aerodynamic between the steady and the pitching oscillating under the same Reynolds number.The aerodynamic characteristics of the airfoil oscillation are further studied by numerical simulation software FLUENT due to the limitation of the experimental conditions.2D unstructured dynamic mesh was realized with the User-Defined Function.Firstly,the pure pitching numerical simulation was been down with the same situation of the experiment and compared the results with each other.And then a serious of numerical simulations on pure pitching,pure plunging,pitching and plunging of the airfoil were carried out on the basic of confirming the reliability of the simulation.The results show: Hysteresis effect of the oscillating airfoil lift coefficient becomes apparent with the increase of the Strouhal number,and the direction of the hysteresis loop changes from counterclockwise to clockwise with the increase of the reduced frequency.The hysteresis effect of lift coefficient is weakened with the increase of oscillating frequency and the have a trend return to linearly proportional to the angle of attack.The lift coefficient increases with mean angle of attack in lower reduced frequency.But the lift coefficient is mainly affected by its motion state instead of angle of attack of the airfoil in a high Strouhal number oscillation.The research of the aerodynamic characteristics of the oscillating airfoil in this paper has some reference value to the power output and load variation on a wind turbine.