Performance Measurement of a Two-Stage Two-Bladed Savonius Rotor

Conventional Savonius rotor is the ancient form of Vertical Axis Wind Turbines (VAWT) rotor which has many advantages such as self-starting, omni-directional, less noisy, suitability for applications like pumping, grinding, sailing etc. However, its efficiency is only in the range of 15%-21%. Investigations are being conducted to improve its efficiency by controlling its design parameters. In this paper the performance of a two-stage two-bladed configuration of the Savonius rotor has been investigated. Experiments are conducted in a subsonic wind tunnel available in the department. The parameters studied are overlap, tip speed ratio, power coefficient (C-p) and torque coefficient (C-t). Overlap ratio of the design was optimized to generate maximum performance of the rotor. The study showed that a maximum C-p of 0.517 was obtained at 9.37% overlap condition. Thus C-p of the rotor is much higher than the conventional Savonius rotor.