Misaligned wind turbine rotors experience uneven loads because of two effects: dissymmetry of lift, and skewed wake effect. Rotor-crafts that have a similar problem introduce various mechanisms to combat this - one of them is to add a δ3-hinge. The hinge provides the blade with an additional degree of freedom to relieve the unbalanced loads; in theory, it is a self-correcting mechanism. In this work, we couple a blade element momentum (BEM) approach for the aerodynamics to a rigid-body model that simulates the hinge rotation. The results from BEM are used to identify the working mechanisms of the hinged rotor and highlight the strengths and weaknesses of such a rotor.

A novel immersed boundary method based on a domain decomposition approach is proposed in the context of a finite element discretisation method. It is applicable to incompressible flows past rigid, deforming, or moving bodies. In this method, unlike most immersed boundary methods, strong boundary conditions are imposed in the regions of the computational domain that are occupied by the structure. In order to achieve this, the proposed formulation decomposes the computational domain by splitting the finite element test functions into solid and fluid parts. In the continuous Galerkin formulation, this produces a smeared representation of the fluid-structure interface. The absence of an immersed boundary forcing term implies that the method itself has no influence on the CFL stability criterion. Furthermore, the stiffness matrix in the momentum equation is sparser than compared with other forcing immersed boundary methods, and symmetry and positive-definiteness of the Laplacian operator in the pressure equation is preserved. As shown in this paper, stability and accurate imposition of boundary conditions make the method promising for high Reynolds number flows. The method is applied to the simulations of two-dimensional laminar flow over stationary and moving cylinders, as well as a moderately high Reynolds number flow past an aerofoil. Good results are obtained when compared with those from previous experimental and numerical studies.

Airborne wind energy systems often use kites made of thin membranes to save material costs and increase mobility. However, this design choice increases the complexity of the aeroelastic behaviour of the system and demands high-fidelity tools. On the aerodynamic side of the multi-physics problem, it is quite challenging to create a high quality body conforming grid due to the complexity of the geometry and the degree of deformation it undergoes. Immersed boundary methods (IBMs) are quite popular in fluid-structure interaction (FSI) problems that involve arbitrarily deforming bodies with complex geometries and are more tolerant to deformations compared to mesh deforming methods like ALE. This paper will look at some of the popular IBMs, outline criteria to evaluate their applicability, and discuss the limitations they have in fulfilling those in problems involving thin membranes.