Abstract
The present study explores the effect of using two porous deflectors on the performance of the Savonius wind turbine compared to only one porous deflector. The numerical simulation is performed to solve the unsteady Navier–Stokes equations using the SST k-ω turbulence model. The porous deflectors under consideration are placed upstream of a Savonius wind turbine. To improve turbine performance, deflector parameters such as porosity, angle, position, and length are varied for one of the deflectors placed near the advancing blade. The second deflector in front of the returning blade is retained in a previously optimized configuration. Then the finalized configuration with two porous deflectors is compared to the previous single porous deflector configuration. At a tip speed ratio of 0.9, the finalized two porous deflector configuration exhibits a 26% higher power coefficient than the single porous deflector case and delivers positive torque throughout the cycle. The maximum variation of torque coefficient in a cycle is found to be 6% lower as well. Due to the increased blockage effect for two deflectors, suitable domain dimensions are also studied to mitigate the overestimation of the performance coefficient. The self-starting capability of the turbine is improved significantly for the azimuthal angle of 80° as well.
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Data will be shared upon request.
Abbreviations
- θ :
-
Azimuthal angle [°]
- β :
-
Angle of the upper porous deflector [°]
- ω :
-
Angular velocity of the turbine [rad/s]
- A :
-
Area swept by the turbine [m2]
- ρ :
-
Density of air [kg/m3]
- D :
-
Diameter of the turbine [m]
- d :
-
Diameter of the bucket [m]
- D r :
-
Diameter of the rotating domain [m]
- μ :
-
Dynamic viscosity of the fluid [kg/ms]
- L 1 :
-
Horizontal distance of the inlet measured from the center of the turbine [m]
- L 2 :
-
Horizontal distance of the outlet measured from the center of the turbine [m]
- X :
-
Horizontal distance of the porous upper deflector from the center of the turbine [m]
- U ∞ :
-
Inlet velocity of the fluid [m/s]
- C 2 :
-
Inertial Resistance [1/m]
- L :
-
Length of the porous upper deflector [m]
- C m :
-
Instantaneous moment coefficient [−]
- C m,avg :
-
Average moment coefficient [−]
- e :
-
Overlap length [m]
- K :
-
Permeability [m2]
- P t :
-
Power [W]
- C p :
-
Instantaneous power coefficient [−]
- C p,avg :
-
Average power coefficient [−]
- ψ :
-
Porosity of the upper deflector [−]
- D L :
-
Lower porous deflector [−]
- D U :
-
Upper porous deflector [−]
- P :
-
Pressure [Pa]
- R :
-
Radius of the turbine [m]
- C ms :
-
Static moment coefficient [−]
- t :
-
Thickness of the bucket [m]
- λ :
-
Tip Speed Ratio [−]
- T :
-
Torque [N.m]
- W 1 :
-
Vertical distance of the upper symmetry wall from the center of the turbine [m]
- W 2 :
-
Vertical distance of the lower symmetry wall from the center of the turbine [m]
- Y :
-
Vertical distance of the porous upper deflector from the center of the turbine [m
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Acknowledgements
We are immensely grateful to Dr. Mohammad Nasim Hasan for the prudent commentary and early review of our work. We want to thank him for giving us his valuable time to guide us.
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Conceptualization: MMHS, and MAH; Methodology: MMHS, and MR; data collection and analysis: MR; simulation: MMHS, MR, MAH, WA, and MFJ; visualization: MMHS, and MR; Writing: MMHS, MR, MAH, WA, and MFJ; investigation: MMHS, MR, MAH, WA, and MFJ; Writing—review and editing: MQI; supervision: MQI; All authors have read and agreed to the published version of the manuscript.
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Saikot, M.M.H., Rahman, M., Hosen, M.A. et al. Savonius Wind Turbine Performance Comparison with One and Two Porous Deflectors: A CFD Study. Flow Turbulence Combust 111, 1227–1251 (2023). https://doi.org/10.1007/s10494-023-00459-6
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DOI: https://doi.org/10.1007/s10494-023-00459-6