Numerical and Experimental Evaluation of High-Efficiency Savonius Type Wind Turbine at Low Reynolds Number

Abstract

Extended Abstract Classical Savonius - type wind turbines (SWT) with semi - circular blades were shown to achieve peak power coefficient (efficiency or c P ) up to 25% [1] . The peak power coefficient values were achieved only at relatively high Reynolds number (Re>800k). This was initially shown only using wind-tunnel investigations, and these results were strengthened by many subsequent numerical studies which have shown good correlation with the experimental data. In recent SWT research, the objective is mostly related to increasing relatively low SWT efficiency. One of the notable SWT blade shape modifica tions to show significant improvement was proposed by Bach and Benes in [2] –[4] . The modified blade shape was composed a straight part in the inner rotor part and a circular - arc (spanning less than 180°) on the outer part. The peak power coefficient was increased from 22% to 28%. D ifferent recent studies attempted further improvement using complex curves such as elliptical [5], spline [6] or multiple smaller quarter [7] , with no major improvement. A major improvement was achieved in numerical shape - optimization studie s with the novel "scooplet - based" SWT [8] with efficiency increased to 37% using 2D CFD and 34% using 3D CFD [9] .