Performance and flow field evaluation of a Savonius rotor tested in a wind tunnel

A renewed interest on Vertical Axis Wind Turbines (VAWTs) arose from their great capacity for integration within urban areas and for applications of distributed generation. In order to be able to highly improve their performance, making them competitive with respect to the more consolidated Horizontal Axis Wind Turbines (HAWTs), it is fundamental to have a deeper comprehension of their fluid dynamic behavior. In order to reach this goal, a two-bucket Savonius rotor has been designed, built from a PVC pipe with a nominal diameter of 200 mm, and tested in the wind tunnel of the Department of Mechanics, Mathematics and Managment (DMMM) of the Politecnico di Bari. The Savonius rotor is connected to an AC brushless servo motor, able to control either the braking torque or the rotational speed. This paper describes the experimental evaluation of the unsteady flow field downstream the rotor by means of a Constant Temperature hot wire Anemometer (CTA). Whilst, for performance analysis, the torque measurements have been obtained directly from the Servo Amplifier torque monitor.