Performance enhancement of vertical axis hydrokinetic turbine using novel blade profile

Abstract

Savonius hydrokinetic turbine is a promising technology for small-scale hydropower generation. The savonius turbine has a simple design and good starting characteristics but suffers from poor performance. In this study, a novel blade profile has been proposed to improve the performance of the conventional savonius turbine rotor. The new blade profile is based on a S1048 airfoil section. The geometry of S1048 airfoil section blades is composed of straight and curved segments. The long straight edge provides larger moment arm and gap flow while the curved segment decreases the effect of negative torque on the rotor. Unsteady RANS CFD simulations have been performed to evaluate and compare the performance of the proposed blade profile. It is shown that the maximum power coefficient of the conventional design can be improved by 14% at a tip speed ratio of 1, by using the new blade profile. The performance of the proposed design has also been evaluated by augmenting an upstream curtain arrangement with the turbine. As a result, an additional 13% increase in the power coefficient was realized when compared with the conventional augmented rotor.