Design and Performance of a Straight-Bladed Darrieus Wind Turbine

In this paper a procedure to maximize the energy production and power coefficient of a Vertical Axis Wind Turbine with straight blades is presented. The Multiple Stream Tube Model was used to predict the performance of the Vertical Axis Wind Turbine with straight blades and five different symmetric airfoils were compared. In particular, NACA 0012, NACA 0015, NACA 0018, NACA 0021 and NACA 0025 were tested. For each considered airfoil and for specific rotor solidity and tip speed ratio maximum wind turbine power coefficient was obtained. Moreover, a methodology for achieving the maximum extracted energy at each wind velocity is presented. Finally, on the basis of the presented results it is possible to conclude that maximum energy production and maximum power coefficient can be achieved using a wind turbine rotor with only two blades.