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Abstract
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The present study proposed a novel porous deflector in front of the Savonius wind turbine to improve the
performance. This new deflector was specifically proposed to minimize the severe effects of the complex wake
zone created behind the conventional solid deflector that had not been investigated yet. This caused a deeper
investigation into the effect of severe negative effects on the turbine performance to achieve an appropriate
design configuration. Therefore, different configuration parameters were taken into account during the numerical process. The unsteady Reynolds-averaged Navier-Stokes equation in conjunction with the SST k-ω
turbulence model was numerically solved. Comprehensive comparisons of torque, power, and flow structures
between deflector configurations and the standard Savonius turbine were performed to illustrate the mechanism
of how the porous deflector improved the turbine performance. Using a porous deflector caused the wind flow
passed through the porous zone resulted in a breakdown of the wake zone behind the deflector. Thereby, the
flow structures became more regular with fewer fluctuations. The results demonstrated that there is an appropriate porosity value to obtain the highest torque and power coefficients. The maximum value of the power
coefficient increased by approximately 10% using the favorable configuration of porous deflector at a tip speed
ratio of 1. The notable observation was that the appropriate configuration increased the static torque coefficient
approximately 2 times in the rotation angles between 0° and 30° which proved the self-starting ability besides
power coefficient enhancement.
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