A 3D unsteady panel method for vertical axis wind turbines

Abstract

A 3D, unsteady, multi-body, free-wake panel method is developed to model a vertical axis wind turbine of arbitrary configuration. The panel code is intended as a design and research tool to capture the 3D nature of a VAWT and its wake. The model contains methods to realistically treat blade-wake interactions, vortex stretching/contraction and viscous diffusion. Validation is demonstrated by comparison with 3D-stereo Particle Image Velocimetry (PIV) and smoke trail studies for a straight-bladed VAWT. New insight into the near wake structure of a VAWT is developed in addition to how this structure changes as a function of tip speed ratio and height-diameter ratio. Tip vortex dynamics are also discussed.