Aeroelastic Modeling of an Airborne Wind Turbine Based on a Fluid–Structure Interaction Approach

The airborne wind turbine (AWT) employs a flying energy conversion to harvest the stronger winds blowing at higher altitudes. This study presents an aeroelastic evaluation of the AWT, which carries a flying rotor installed inside a buoyant shell. A considerable aerodynamic impact on the structural integrity of the full-scale system is modeled using a fluid–structure interaction (FSI) approach. Both the fluid and structure models are formulated separately and validated using a series of benchmark numerical data. To analyze the structural aeroelasticity, the aerodynamic loads from the fully resolved computational model are coupled using a one-way FSI on the structural model of the blade and shell to perform the non-linear static analysis. For a detailed investigation, various wind loads from the bare and shell rotor configurations are imposed on the flexible structure. The generated torque, aerodynamic loads, tip deflection, stress estimation and operational stability of the proposed energy system are computed. The tip deflection is 18% more in the shell rotor compared to the bare rotor at rated conditions, while an average increase of 54% more tip deflection was observed for every 4 m/s increase in wind speed. The non-linear aeroelastic characteristics in each case are found to be within the chosen design criteria, according to material, operational speed and structural limits. Most importantly, the significant power gain justifies the structural response of the blade to withstand the shell-induced loads at rated conditions in the shell configuration.