The FAST/ADAMS/AeroDyn system of codes has been widely used to perform the aero-structural analysis of conventional wind turbine blades. Recent advances in blade design involve the development of aeroelastic tailored blades with large amounts of sweep, and blades with winglets. However, the existing Blade Element Momentum (BEM) approach in AeroDyn is limited to straight blades and does not account for sweep or dihedral effects. The goal of this work is to obtain higher fidelity aerodynamic loads predictions for such advanced blade designs. A Vortex Line Method (VLM) for computing aerodynamic loads has been coupled to ADAMS through modification of the existing AeroDyn interface. The VLM approach adopted here adds fidelity by modeling the effects of sweep, dihedral, 3D wakes, and wake dynamics. An existing steady/unsteady VLM code with these capabilities was restructured to allow its integration with AeroDyn. The FAST routines from NREL, which are used as a preprocessor to ADAMS, and the ADAMS/AeroDyn interface itself, were also modified to create an ADAMS model that properly accounts for the curvature of the blade that occurs when large amounts of sweep or winglets are present. The resulting ADAMS/VLM model was compared to the original ADAMS/BEM model for a straight blade and for a highly swept blade. The model was also applied to blades with pressure-side and suction-side winglet configurations. The BEM and VLM models give similar aero predictions for the straight blade, as expected. The induced twist and blade deformations are found to be more similar for the two methods than the aerodynamic loads. Computations were made for the blades with the winglets at different wind speeds and different pitch settings, and results were obtained for blade deflection, induced twist, and thrust and torque force distributions.
Structural Analysis of Complex Wind Turbine Blades: Flexo- Torsional Vibrational Modes
