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SUMMARYIn this paper, we target more advanced fluid-structure interaction (FSI) simulations of wind turbines than reported previously. For this, we illustrate how the recent advances in isogeometric analysis of thin structures may be used for efficient structural mechanics modeling of full wind turbine structures, including tower, nacelle, and blades. We consider both horizontal axis and vertical axis wind turbine designs. We enhance the sliding-interface formulation of aerodynamics, previously developed to handle flows about mechanical components in relative motion such as rotor-tower interaction to allow nonstationary sliding interfaces. To accommodate the nonstationary sliding interfaces, we propose a new mesh moving technique and present its mathematical formulation. The numerical examples include structural mechanics verification for the new offshore wind turbine blade design, FSI simulation of a horizontal axis wind turbine undergoing yawing motion as it turns into the wind and FSI simulation of a vertical axis wind turbine. The FSI simulations are performed at full scale and using realistic wind conditions and rotor speeds.

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A fluid–structure interaction (FSI) validation study of the Micon 65/13M wind turbine with Sandia CX-100 composite blades is presented. A rotation-free isogeometric shell formulation is used to model the blade structure, while the aerodynamics formulation makes use of the FEM-based ALE-VMS method. The structural mechanics formulation is validated by means of eigenfrequency analysis of the CX-100 blade. For the coupling between the fluid and structural mechanics domains, a nonmatching discretization approach is adopted. The simulations are done at realistic wind conditions and rotor speeds. The rotor-tower interaction that influences the aerodynamic torque is captured. The computed aerodynamic torque generated by the Micon 65/13M wind turbine compares well with that obtained from on-land experimental tests.

Full-scale, 3D, time-dependent aerodynamics modeling and simulation of a Darrieustype vertical-axis wind turbine (VAWT) is presented. The simulations are performed using a moving-domain finite-element-based ALE-VMS technique augmented with a sliding-interface formulation to handle the rotor-stator interactions present. We simulate a single VAWT using a sequence of meshes with increased resolution to assess the computational requirements for this class of problems. The computational results are in good agreement with experimental data. We also perform a computation of two side-by-side counterrotating VAWTs to illustrate how the ALF-VMS technique may be used for the simulation of multiple turbines placed in arrays.