The Savonius wind turbine is known for its simplicity, outstanding cost-effectiveness and low noise, making it ideal for wind energy harvesting in urban areas. However, its success is hampered by the low coefficient of performance. Several geometrical modifications have been proposed by researchers to improve its performance. The present study aims to investigate the impact of the endplate addition on the coefficient of performance of the Savonius wind turbine. The unsteady Reynolds Average Navier Stokes equations and the turbulence equations corresponding to SST κ-ω were solved using the commercial CFD package ANSYS FLUENT. An endplate-integrated 3D model and an endplate-free 3D model of the same geometrical configuration of 1 m diameter and height were simulated under the condition of tip speed ratio 0.8. The extracted results were compared with the existing experimental and numerical data under the same conditions and a close agreement was reached. The endplate-filled turbine showed a significant increase in performance. The lift and drag coefficients were enhanced by 4 and 1.8 times, respectively. Flow contours of pressure, velocity and turbulence intensity were obtained at an angular rotation of 90° where there was a maximum increase in performance to explain how the endplate brings about the change.
The Savonius wind turbine is known for its simplicity, outstanding cost-effectiveness and low noise, making it ideal for wind energy harvesting in urban areas. However, its success is hampered by the low coefficient of performance. Several geometrical modifications have been proposed by researchers to improve its performance. The present study aims to investigate the impact of the endplate addition on the coefficient of performance of the Savonius wind turbine. The unsteady Reynolds Average Navier Stokes equations and the turbulence equations corresponding to SST κ-ω were solved using the commercial CFD package ANSYS FLUENT. An endplate-integrated 3D model and an endplate-free 3D model of the same geometrical configuration of 1 m diameter and height were simulated under the condition of tip speed ratio 0.8. The extracted results were compared with the existing experimental and numerical data under the same conditions and a close agreement was reached. The endplate-filled turbine showed a significant increase in performance. The lift and drag coefficients were enhanced by 4 and 1.8 times, respectively. Flow contours of pressure, velocity and turbulence intensity were obtained at an angular rotation of 90° where there was a maximum increase in performance to explain how the endplate brings about the change.
“…Since the C P value of the Savonius wind turbine as a function of the Reynolds number has a parabolic graph form, it increases to the maximum C P at a certain Reynolds number and decrease after passing its maximum point [11,12].…”
Savonius wind turbine with Bach-profile blades is considered in this study. Previous studies have shown that a rotor with the Bach-profile blade produces better performance than a standard Savonius turbine. This study focuses on the blade shape factor variations of the Bach-profile blade to give the best performance. Two-dimensional unsteady simulations are performed with moving mesh. The configuration being tested is the Savonius rotor with Bach-profile blades with an arc angle of 135 • . The blade shape factor is varied 0.2, 0.3, 0.4 at a constant freestream velocity of 4 m/s, with a corresponding Reynolds number of 20,000. The k-ω Shear Stress Transport turbulence model was used, with secondorder discretization schemes for the pressure and momentum equations. The boundary conditions were set as velocity inlet for the inlet, outflow for the outlet, and walls for the blade surfaces. The top and bottom sides were set as symmetric. Results showed that the configuration with a shape factor of 0.4 gave the best performance among the others. This configuration gave a higher moment coefficient and power coefficient of about 6.8% and 7.3%, respectively. Results extracted from the simulation includes the flow structure, and the distribution of the pressure coefficients along the blade surface.
“…The wind tunnel arrangement with geometrical parameters is illustrated in Figure 5. This dimension is the optimum design proposed in [26]- [27], which has the length of the curtain blades (l1=45 cm and l2=52 cm) and the angles of the blades (α= 45° and β =15°). Construction of this deflecting tunnle is simple and cheap.…”
<p>Savonius wind turbines have advantages of self-rotating at low speed wind, high starting torque, and less noise generation. However, they have low electric power generation capacity. This paper presents electric power generation improvement for small Savonius wind turbines when operating at low-speed wind of 1-6 m/s by using optimal Bach-type blades, twist blades and a wind tunnel. The turbine prototypes with the optimum diameter and height of 32 cm were developed with 3 different blade types: conventional semicircular blades, Bach-type blades and twisted 15° blades and a wind tunnel. The experimental results showed that the Savonius wind turbine with Bach-type generated highest electric voltage, which was 19.3% and 7.6% higher compared to conventional blades and twisted 15° blades. The additional wind tunnel could improve electric power generation efficiency by approximately 21.4% compared to the turbines without the tunnels.</p>
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