Unsteady Flow Simulation and Dynamic Stall Behaviour of Vertical Axis Wind Turbine Blades

This paper presents a computational study of a rooftop size vertical axis wind turbine with straight blades (H-type turbine). The computational model solves for the two-dimensional and three-dimensional unsteady flow fields around the turbine based on the unsteady Reynolds averaged Navier-Stokes equations and a sliding mesh technique to connect the far-field fixed mesh to the near field rotating mesh around the rotor. Interesting flow features such as dynamic stall around the blades and the interaction of the blade wakes with the following blades are illuminated. Comparison of the 2D and 3D simulations highlight strong three dimensional effects, including the blade tip losses and the effects of the blade supporting shaft and arms. These effects significantly degrade the performance of the VAWT under investigation, pointing a way for improving VAWT designs.