3D CFD study of a DeepWind demonstrator at design, off-design and tilted operating conditions

Abstract

Energy transition, towards increased renewables, demands for reliable, efficient, and innovative technical solutions, at acceptable cost. Wind energy conversion exhibits one of the greatest potential, mainly in off-shore deployment. Vertical-axis wind turbines are characterized by a reduced wave recovery and enhanced power output, which boost the installation of bigger capacity turbines, properly cluster to maximize the farm density. These two requirements entail deeper understanding of the wake physics and detailed description of the machine performance. A careful 3D CFD investigation, supported by experimental validation, is carried out to define the relevant flow mechanism of a lab-model, DeepWind demonstrator, in upright and tilted condition. The results show how the performance is varying along the span, and how it is affected by a skewed flow. The lower part of the machine benefits from combined effect of blade curvatures and rotor inclination. A thorough description of the complex vortical field complements the performance data, and provide useful considerations apt for promoting the design of future vertical-axis wind turbines, for floating off-shore applications. The performance parameters are then computed for a full-size rotor to show how the Reynolds effect play a relevant role in the machine aerodynamics of bigger capacity turbines.