Unsteady dynamic load and output performance of the rotor using the dynamic wake theory

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ABSTRACT To accurately calculate the unsteady dynamic load and output performance of the rotor in the stand-alone large-scale wind turbine, a novel added mass force expression m A = 128 / 75 ρ R 3 is derived and corresponding dynamic wake model is established using the acceleration potential flow theory and the blade element momentum in the present study. Moreover, induced velocity delay, wind shear, and yaw are considered in the proposed model. Referring to IEC61400-1 standard of the wind turbine, numerical models of turbulence, gust and wind direction change are established to investigate the output performance of the rotor under the combined effect of aerodynamic force, gravity, and centrifugal force. The obtained results show that the axial load and flapwise bending moment of the blade root are mainly determined by the axial aerodynamic component, while the tangential load and edgewise bending moment are mainly determined by the gravity component of the blade. It is found that the wind shear has a significant impact on the axial load and flapwise bending moment. Meanwhile, the axial thrust and rotor power are mainly affected by the inflow wind speed. It is observed that when the yaw angle exceeds 9.25°, the axial thrust and power of the rotor decrease obviously. The research results are compared with the experimental data from the NREL, it is found that the proposed model provides a new choose for the calculation of added mass force, and it has more calculation accuracy compared with classical BEM method in the prediction of unsteady dynamic load and output performance of the rotor.