Winglets are commonly used in aircraft to reduce induced drag and thus fuel costs. The efficiency of a winglet is related to its geometry (shape, orientation to the plane of the wing, flow regime on the wing). By extending the use of winglets to wind turbine blades, it is tried to estimate the improvement of their performances and to find the optimum geometry and configurations. That is why numerical investigations are carried out for several winglets configurations, for a turbulent flow regime. The solutions considered "optimal" are used for the blade design of a wind turbine with a horizontal or a vertical axis. The aerodynamic performances of the wind turbine are evaluated using 3D numerical simulation for two configurations: rotor with blades using winglet and rotor with blades without winglets.

The RANS (Reynolds Averaged Navier-Stokes) model, combined with Realizable k-ε and SIMPLE algorithm are used as they have an acceptable computational cost and reasonable accuracy.

Numerical results confirm an increase in the efficiency of the wind turbine due to the presence of winglets on the blades.

Key words   winglets, wind turbine performances, CFD