전산유체/전산구조 연계 방법을 이용한 후퇴각이 있는 수평축 풍력터빈 로터 블레이드의 공탄성 특성 예측

Abstract

The aeroelastic characteristics for the backward swept blade of a horizontal axis wind turbine were examined by using a coupled CFD/CSD method as the fundamental research for a bend-twist coupled (BTC) blade. The aerodynamic loads were obtained from the three-dimensional, incompressible, Navier-Stokes CFD flow solver based on unstructured meshes. The elastic behavior of the blade was calculated by using an FEM-based CSD solver utilizing a nonlinear coupled flap-lag-torsion beam theory. The calculations were made for the blade of the NREL 5MW wind turbine with backward swept angle. Compared to the straight rotor blade, flapwise deflection toward the tower and edgewise deflection toward the leading edge of the backward swept blade were decreased; otherwise, its torsional deflection in nose-down direction was significantly increased. Due to the blade deformations that decreased its effective angle-of-attack, the aerodynamic loads applied to the swept blades were remarkably reduced compared to the straight rotor blade. In addition, the root bending moments were also influenced by the swept-back configuration of the blade. Due to the aerodynamic loads reduction of the backward swept blade, the root bending moments in the edgewise and flapwise directions were decreased, although the torsional bending moments were significantly increased.