Performance evaluation of a two-blade savonius wind turbine with manually adjustable blade overlap

Abstract

Savonius wind turbines offer a simple, cost-effective solution but are limited by low efficiency due to negative torque. The aim of this study is to enhance the functionality of a two-blade vertical-axis Savonius turbine by incorporating a manually-adjustable blade overlap mechanism. In this study, the primary objective is to assess the impact of varying overlap ratios on efficiency and to determine the optimal configuration for enhancing small-scale energy generation. The fabricated Savonius wind turbine, equipped with manually adjustable blade overlap, was subjected to a series of tests in the Department of Scient and Technology Wind Tunnel at Central Philippine University. The testing process was commenced with a specified overlap ratio, and the wind speed was varied from 4 m/s to 8 m/s. Various parameters were recorded, and subsequently, data such as CP and TSR were calculated based on these parameters. As demonstrated by the testing, the Savonius wind turbine exhibited a cut-in wind speed of 4 m/s. The calculated results indicated that an overlap ratio of 0.3 achieved the highest coefficient of performance among the tested wind speeds. However, a 0.2 overlap ratio achieved a higher CP at 6 m/s. Furthermore, the testing determined the wind speeds at which each overlap ratio operated efficiently based on their respective CP. The findings indicate that modifying the overlap ratio can optimize energy conversion by enabling the turbine to adapt to variable wind conditions more effectively.