Analysis of the coupled aeroelastic wake behavior of wind turbine

Abstract

Abstract With the development of wind energy in recent years, the aeroelastic performances and the wake characteristics of a wind turbine and their effect on the downstream wind turbine have become research priorities. However, traditional aeroelastic analysis tools based on the Blade Element Momentum theory (BEM) cannot calculate the wake characteristics of a wind turbine. This study focuses on the coupled aeroelastic wake behavior of the wind turbine and developed a new tool called ALFBM, which combines the Actuator Line Method (ALM) and the nonlinear finite element Beam theory. The coupled aeroelastic wake behavior of a single NREL 5\xa0\xa0MW wind turbine under the inlet velocity of 8 m/s and 11.4 m/s are studied. The aerodynamic and structural results such as power, thrust, natural frequencies, and tip deflections are compared with the results of former researches to verify this new analysis tool. Also, these results show that the stress stiffening effect and the nonlinear bending effect significantly decrease the frequency of flapwise mode by 12.7% and the tip deflection by 31%. It is found that the modal shape of every asymmetry flapwise mode varies periodically during the wind turbine rotation. The wake results demonstrate that the recovery of the velocity and vorticity in the far wake region (>5D) are underestimated when the deformation of the wind turbine blades are neglected.