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Experimental and simulation analysis for performance enhancement of elliptical savonius wind turbine by modifying blade shapes

Abstract

Savonius turbines are drag-based rotors which operate due to a pressure difference between the advancing and retreating blades. After going through an exhaustive literature review, it was realized that the Savonius wind turbines are an applicable option at low wind speed areas, where the counterpart of these turbines cannot work efficiently. Nevertheless, the existing design is still under research to make it more applicable in urban areas. Therefore, the research objective was to develop and test an elliptical Savonius wind turbine to improving its performance in terms of power and torque coefficients by modifying blade shapes and overlap ratio. In the beginning, a series of 2D unsteady simulations (CFD-Fluent version 19.1) of the Savonius elliptical turbine has been performed to study the overlap ratio of blades and the effect of the turbulence models. Conventional elliptical Savonius turbine was modified by changing the overlap ratio from the value (OR=0.15) to (OR=0.2) and called as the Model-A. Then, the concave surface of the blade Model-A was modified (as zigzag shape) and called as Model-B. The blade shape of the Model-B was modified by adding bypass channels for each blade to creating new configuration was called the Model-C. The experimental work begins with the manufacturing of the models (A, B and C) of the blade using 3D printing technology. Models were tested by the wind tunnel in Aerodynamic laboratory (UTHM) with four cases of wind velocity. 2D simulation result for Model-A at OR= 0.2, where the increase in maximum power coefficient value obtained was 3.85% and 7.69% compared to overlap ratio (0.15 and 0.1), respectively. The result of the experimental test was obtained the maximum power coefficient (0.296, 0.292, 0.291, and 0.295) at wind velocity (6 m/s, 8 m/s, 9 m/s, and 10 m/s), respectively for Model-B. The Model-C result in the maximum power coefficient (0.28) compared with Model-A (0.26). The 3D unsteady simulation also has been done to visualisation the behaviour of flow around Model-B and it show a good agreement with experimental test results

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