Aeroelasticity is the study of the dynamic interaction between unsteady aerodynamics and structural dynamics on flexible streamlined bodies, which may include rigid-body dynamics. Industry standard solutions in aeronautics and wind energy are built on the assumption of small structural displacements, which lead to linear or quasi-linear theories. However, advances in areas such as energy storage and generation, and composite material manufacturing have fostered a new kind of aeroelastic structures that may undergo large displacements under aerodynamic forces.In particular, solar-powered High-Altitude Long-Endurance (HALE) aircraft have recently seen very significant progress. New configurations are now able to stay airborne for longer than three weeks at a time. Extreme efficiency is achieved by reducing the total weight of the aircraft while increasing the lifting surfaces' aspect ratio. In a similar quest for extreme efficiency, the wind energy industry is also trending towards longer and more slender blades, specially for off-shore applications, where the largest blades are now close to 100-m long.These longer and more slender structures can present large deflections and have relatively low frequency structural modes which, in the case of aircraft, can interact with the flight dynamics modes with potentially unstable couplings. In the case of offshore wind turbines, platform movement may generate important rotor excursions that cause complex aeroelastic phenomena which conventional quasi-linear methods may not accurately capture.

The paper investigates the use of vortex methods in the computation of important flows for wind turbine aerodynamics. These flows are characterised by inflow velocity unsteadiness, spatial variations and non-zero spanwise component. First, computational vortex methods are shown to match analytical solutions on simple geometries. Second, these geometries will be studied to reveal the effects of these flows on airfoil aerodynamics: unsteady damping and load reduction when subjected to side slip or spanwise inflow velocity variations. Finally, vortex methods will be compared with traditional BEM methods in full wind turbine configurations under real operating inflows such as shear, yaw and turbulence which are characterised by unsteadiness and three-dimensional effects. Vortex methods allow quantifying the error of BEM methods for these conditions.

This work presents various improvements made to the Unsteady Vortex Lattice Method (UVLM) integrated into the open-source, nonlinear aeroelastic simulation environment SHARPy. The UVLM is extended by non-lifting body effects, polar corrections, and a new wake discretization scheme. The theory behind these enhancements is discussed and successfully verified. Finally, some of these enhancements are employed on a flexible aircraft demonstrator model. The results indicate an influence of the fuselage on the aeroelastic behavior of the wing, which becomes increasingly important for larger wing deformations and fuselage diameters. The polar corrections provide valuable refinements to the aerodynamic forces and moments, and the new wake discretization scheme significantly speeds up the simulations.

The aim of this work is to present a detailed code-to-code comparison of two Large-Eddy Simulation (LES) solvers. Corresponding experimental measurements are used as a reference to validate the quality of the CFD simulations. The comparison highlights the effects of solver order on the solutions, and it tries to answer the question of whether a high order solver is necessary to capture the main characteristics of a wind farm. Both solvers were used on different grids to study their convergence behavior. While both solvers show a good match with experimental measurements, it appears that the low order solver is more accurate and substantially cheaper in terms of computational cost.