https://orcid.org/0000-0001-9593-5180
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ABSTRACT
The present numerical study employs a passive flow control augmentation mechanism to enhance the hydrodynamic performance of the Savonius hydrokinetic turbine. Two cylindrical deflectors guide the flow over the Savonius rotor blades. The effectiveness of placing the deflectors is examined by positioning them upstream of the returning and advancing blades. The Savonius hydrokinetic rotor’s efficiency is improved by incorporating Deflector1 to decrease the counteracting torque from the returning blade and Deflector2 to magnify the positive torque produced by the advancing blade. The study focuses on finding a suitable position () and size (
) of Deflector1 while keeping the size (
) and position (
and ⍺) of Deflector2 fixed. The diameter of Deflector1 (
) changes as
=0 .15, 0.20, 0.25, 0.30, and 0.35 for each position,
of 1.35, 1.65, 1.95, and 2.25. The study reports that the augmented Savonius turbine operates most efficiently at
=0 .15,
= 1.65, corresponding to a tip speed ratio of 0.9. The deflector-assisted Savonius hydrokinetic turbine enhances the power coefficient (CP) by 54.1% in comparison to the ordinary Savonius rotor lacking deflectors. Further, utilizing cylindrical deflectors upstream of the Savonius hydrokinetic rotor improves the operating TSR range of the Savonius hydrokinetic turbine.
Nomenclature
| CT | = | Coefficient of Torque |
| CTavg | = | Coefficient of Torque (Average) |
| CP | = | Coefficient of Power |
| CPmax | = | Coefficient of power (Max) |
| D | = | Diameter of Rotor (m) |
| d | = | Diameter of Rotor blade (m) |
| d1 | = | Diameter of Deflector1 |
| d2 | = | Diameter of Deflector2 |
| d1/d | = | Diameter ratio |
| k | = | Kinetic energy – turbulent (m2/s2) |
| L1 | = | Deflector1’s horizontal position in relation to the rotor axis (m) |
| L2 | = | Deflector 2’s radial location with respect to the rotor axis (m) |
| L1/d | = | Length ratio |
| y+ | = | Measurement of wall distance |
| Greek Symbols | = | |
| ω | = | Specific dissipation rate (s−1) |
| ⍺ | = | Deflector2’s angular position with respect to the rotor’s horizontal axis (°) |
| ε | = | Turbulence dissipation rate (m2/s3) |
| θ | = | Azimuth angle of rotor (°) |
| Abbreviations | = | |
| CFD | = | Computational Fluid Dynamics |
| SIMPLE | = | Semi-implicit Method for Pressure Linked Equations |
| SST | = | Shear Stress Transport |
| TSR | = | Tip Speed Ratio |
| URANS | = | Unsteady Reynolds Averaged Navier Stokes |
Acknowledgements
The authors acknowledge the support received from the IITK computer center (www.iitk.ac.in/cc) in providing the necessary resources for conducting computational tasks, analyzing data, and preparing the article.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Data availability statement
The data supporting this study’s findings can be obtained from the corresponding author upon making a reasonable request.
Additional information
Notes on contributors
Omveer Singh
Omveer Singh is pursuing his M.S. from the Department of Sustainable Energy Engineering, Indian Institute of Technology Kanpur, 208016, Kanpur, India. His work mainly focuses on numerical investigations of hydrokinetic turbines.
Gaurav Saini
Dr. Gaurav Saini is presently working as an Assistant Professor in the Department of Mechanical Engineering, at Harcourt Butler Technical University, 208002, Kanpur, India. Dr. Saini has Post-Doctoral Fellow experience with the Department of Sustainable Energy Engineering, Indian Institute of Technology Kanpur. He received his Ph.D. in Turbomachines (Hydrokinetic Turbines) in the year 2020 and M. Tech, (Fluid Machinery and Energy Systems) in the year 2014 from the Indian Institute of Technology Roorkee, Uttarakhand India. His research areas include Renewable Energy (Hydrokinetic Energy, Wind Power, and Biomass), Computational Fluid Dynamics (CFD), and Fluid Mechanics and Turbomachines; Fluid Power. He has published 32 research publications on renewable energy technologies in different international journals of repute, filed 3 Indian patents, wrote 8 book chapters, and Co-Edited 3 books. Dr. Gaurav is skilled in Computational Fluid Dynamics (CFD), Modeling of various renewable energy resources viz. wind, marine, solar, and hydrokinetic energy for rural applications, wind and hydrokinetic- Technology selection and design, Installation strategies, Performance evaluation, and O&M issues.
Ashoke De
Dr. Ashoke De is currently a Professor in the Department of Aerospace Engineering and has a joint appointment in the Department of Sustainable Energy Engineering at the Indian Institute of Technology Kanpur, 208016, Kanpur, India. Dr. De received his Ph.D. degree in Mechanical Engineering from Louisiana State University, USA in 2009. Before joining IIT Kanpur, he worked as a post-doctoral scholar at the Technical University of Delft (TU-Delft), Netherlands, and as a Research Engineer at GE Global Research in Bangalore, India. He is an AvHumboldt Fellow, AIAA Associate Fellow, Fellow of West Bengal Academy of Science and Technology, Associate Editor of the International Journal of Energy for a Clean Environment, and currently a member of APS, AIAA, ASME, SIAM, FMFP, ISHMT, and Combustion Institute. Dr. De leads large-scale initiatives in the modeling of turbulent flows at IIT Kanpur. His current research interests include modleing of multiphase flows, high speed flows, Fluid-Structure interactions (FSI), and Energy Harvesting.