Performance Improvements for a Vertical Axis Wind Turbine by Means of Gurney Flaps

A numerical study was carried out to investigate the effects of a Gurney flap on the aerodynamics performance of the NACA 0018 aerofoil and an associated three-blades rotor of a H-type Darrieus wind turbine. The flow fields around a single aerofoil and the Vertical Axis Wind Turbine (VAWT) rotor are studied using URANS. The height of Gurney flap ranges from 1% to 5% of the aerofoil chord length. The results show that the Gurney flap can increase the lift and lift-to-drag ratio of the aerofoil as associated with the generation of additional vortices near the aerofoil trailing edge. As a result, adding a Gurney flap can significantly improve the power coefficient of the VAWT at low tip speed ratio, where it typically gives low power production. The causing mechanism is discussed in detail, pointing to flow separation and dynamic stall dela