Combined Aero-Structural Optimization of a Φ-Shaped Darrieus Vertical Axis Wind Turbine Operating Under Intracycle RPM Control

Vertical Axis Wind Turbines (VAWTs) are becoming increasingly viable for offshore wind in recent years. The unique azimuth-dependent dynamics of a VAWT allow for novel control strategies such as intracycle RPM control, where the rotational speed of the rotor is varied within each revolution to maximize power production or reduce fatigue loading. However, existing studies have only explored these benefits using a fixed rotor geometry. In contrast, aero-structural optimizations have assumed a constant RPM control strategy, which leaves out additional considerations of loads and power production in the optimization process. To the best of the authors' knowledge, no studies have combined aero-structural optimization of a VAWT with various control considerations into a single framework. The work presented here thus closes the loop on this multidisciplinary design problem, building toward a control co-design (CCD) approach and culminating in a coupled aero-structural-control (ASC) design optimization of a Φ-shaped Darrieus VAWT.