Experimental Investigations on the Performance Characteristics of a Modified Four Bladed Savonius Hydro-Kinetic Turbine

Abstract

Torque variation along the angular positions of the rotor blade and lower efficiency are the main drawbacks of Savonius turbine. To overcome these problems several attempts have been made by the researchers in the recent past.  In this work, an attempt has been made to increase the torque along the angular positions where the torque is low, by placing a set of additional blades called secondary blades in front of the concave side of main rotor blades. These secondary blades are interacting with the flowing fluid when the main blades are not in action. The performance of the modified Savonius turbine is compared with the conventional single blade 0 overlap and 0.2 overlap Savonius turbines, by carrying out the experiments in the open irrigation canal of size 42 cm x 45 cm. Results shows that, the efficiency is improved from 16 % to 19% and the torque values increased along the angular positions of 90°, 120°, 270°, 300°, 330°.  From the observations, it has also been noted that, the modified four bladed Savonius turbine rotates smoothly in comparison with the conventional Savonius. The negative torque a common problem in conventional Savonius is also effectively eliminated in the modified design.