Aeroelastic stability analysis of a wind turbine blade section with trailing edge flap using a flexible unsteady blade elements momentum theory

This study aims to develop an unsteady aerodynamic model and blade element momentum theory to analyze the aeroelasticity of a rotating airfoil with trailing edge flap of a wind turbine blade. The Hamiltonian principle serves to define the equations of motion. Theodorsen and Loewy aerodynamic models alone and together with blade element momentum (BEM) theory are applied to form aeroelastic equation of motion. Theodorsen or Loewy aerodynamics together with BEM theory present a new flexible unsteady blade element momentum aerodynamic model. Verification of developed aeroelastic equation motion is conducted on a fixed and a rotating airfoil successfully. Flutter boundary results imply the superiority of proposed aerodynamic model. Besides, we investigated theoretical effects of pitch and flap stiffness changes on flutter. The derived results demonstrate that pitch stiffness is the dominant mode on flutter boundary of the rotating blade section with a control surface.