A Numerical Study of Wind Turbine Airfoil Combined Oscillations Considering Phase Difference under Yaw Loads

In order to further improve the operating efficiency of wind turbines and explore the aerodynamic performance of the complex motion of wind turbine blades under yaw loads. In this study, the change in the angle of attack of the blade section airfoil under yaw load can be modeled as an oscillating airfoil and combined with the blade's flapwise motion. The NREL S809 airfoil are chosen for the research, based on the SST k-ω turbulence model with transition correction, under the condition of Reynolds number of 10 6 . The effect of phase difference on its aerodynamic performance under combined flapwise and pitching motion in various flapwise amplitudes and working conditions were analyzed. For the combined oscillations, the effects of the flapwise amplitude ( h ) in the range of 0.2≤ h ≤0.5 are investigated with the phase differences of Φ=±3π/4, ±π/2, ±π/4, 0. The results show that the phase difference between the pitching motion and the flapping motion and the different flapping amplitudes can have a large impact on the aerodynamic performance of the airfoil during dynamic stall, but the degree of influence is greatly different in different situations.