Abstract
In the present study the effect of distance between five vertical Savonius rotors « Gap » on the total performance of the wind farm rotors is investigated. Numerical computations are conducted for a single Savonius turbine, and for the five clustered turbines aligned in perpendicular direction with respect to the upstream wind velocity. The study is carried out using ANSYS FLUENT commercial code and the moving mesh approach for the rotating zones is used. The turbulence model adopted in this work is the k-ω shear stress transport (SST) model. Numerical approach was first validated with previously published experimental and numerical data for a single rotating Savonius rotor case with semi-circular blades. Then, an improvement process based on the modification of the blades profiles to an elliptical shape was adopted. Subsequently, the change in distance between the five vertical Savonius rotors « Gap » has been considered with values of 0.25, 1 and 1.4 times the rotor radius (R). Results show that the Gap = 1R provides the optimum power coefficient for the wind farm rotors. However, the generated wake zone behind the five aligned rotors for this value is more important in particular for the 90 ° angle of the advanced and returned rotor blades. The field efficiency defined by the total power ratio of the five isolated rotors to the total power of the wind farm with five Savonius rotors is around 67%. All these geometrical considerations and propositions made it possible to define an optimal wind farm rotors arrangement.
