Numerical investigation of azimuth dependent smart rotor control on a large-scale offshore wind turbine

The smart fatigue load control of a large-scale wind turbine blade was numerically investigated on our newly integrated aero-servo-elastic platform with emphasis on the effect of azimuth angles. It was found that the smart control effectively reversed the phases of the flapwise aerodynamic force or the acceleration through the controllable deformable trailing edge flap (DTEF) activation within most of rotor azimuth angle range, turning in-phased flow-blade interaction into an anti-phased one at primary 1P mode, significantly enhancing the damping of the fluid-structure system and subsequently contributing to the greatly attenuatedflapwise fatigue loads on the blade and turbine performances. This aero-elastic control physics was most drastic as the investigations were focused on the case beyond the rated wind velocity, leading to the maximum reduction percentages in the time-averaged and azimuth-averaged fatigue loads up to about 30.0%, in contrast to the collective pitch control method. In addition, the finding pointed to a crucial role that the suppression of the coupled flow-blade system dependent on azimuth angles played in the smart blade control, which might guarantee better effectiveness if it would be considered in the development of the DTEF controller.