Optimizing of a wind turbine rotor by CFD modeling

The present work is concerning the optimization of the wind turbine rotor profile to improve performances. Energy output production losses are often due to turbulence and wake effect around turbines downstream, so it is good to design wind farm in order to space wind turbine about 5 and 9 rotor diameters be apart in the prevailing wind direction, and between 3 and 5 diameters apart in the direction perpendicular to the prevailing winds, in order to avoid too much turbulence around the turbines downstream. Spacing between turbines together land use and the cost of connecting wind turbines each other and to the electrical grid have a significant weight in the wind farm realization costs. Hence, it would be a relevant gain to have turbines with smaller rotor diameter but which are able in producing the same energy output that largest rotor wind turbine produce. Different configurations for the wind turbine rotors can increase the power production for a given blade length, making them attractive on wind farm sites, especially with design restrictions on the rotor radius. This work in aimed to understand how the different rotor geometries influence the wake lengths and the turbulence behind wind turbine, in order to verify and quantify the gain in wind turbine spacing. In particular the present paper describes the numerical investigation of the aerodynamics around a wind turbine blade with and without a winglet using Computational Fluid Dynamics, CFD. The purpose of adding a winglet to a rotor blade design is to decrease the induced drag from the blade by changing the downwash distribution. CFD simulations will be done in order to achieve the above described objectives, studying in particular blades turbines with and without winglets, and evaluate the mechanical power increment.