Studies on role of twist angle on performance of Savonius hydrokinetic turbine variants

Thochi Seb Rengma and P.M.V. Subbarao

Renewable Energy, 2025, vol. 241, issue C

Abstract: Savonius hydrokinetic turbine (SHKT) is a drag-based turbine which can be a viable source of electricity using rivers, canals etc. The fluctuation in moment coefficient is an important parameter impacting the shaft vibration and turbine instability, resulting in high fluctuation in electrical power. It is desirable for an optimized turbine to have a greater power coefficient (Cp) as well as less moment fluctuation during a full rotation, which can be achieved by optimizing the blade profile and twist angle. The twist angle of semicircular blades was varied from 0⁰ to 180⁰ to study the turbine efficiency and moment fluctuation. Commercial software CFD Fluent 19.2 was used for computational simulations to optimize the blade. A 3D geometry with Reynolds Averaged Navier Stokes (RANS) equations and transient boundary condition was used for the analysis. The turbine blade with a twist angle of 120⁰ was found to have the highest Cp and much lower moment fluctuation than straight blade. Same twist angle when applied on the blade profile generated using Bezier curve increased the value of Cp further by 14.7 %. That novel blade was fabricated for experimental testing, and the computational results were found to be closely matching with experimental results with an error of 4.2 % only. The novel blade achieved a maximum Cp of 0.218 at tip speed ratio of 0.8. The Cp and moment fluctuation of the novel blade profile was found to be 21 % higher and 61.1 % lower, respectively when compared to the conventional straight semicircular blade.

Keywords: Hydrokinetic turbine; Savonius turbine; Power coefficient; Bezier curve; Twist angle (search for similar items in EconPapers)
Date: 2025
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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:241:y:2025:i:c:s0960148124023711

DOI: 10.1016/j.renene.2024.122303

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