Savonius vertical axis wind turbines (VAWTs) typically suffer from low efficiency due to detrimental drag production during one half of the rotational cycle. The present study examines a stator assembly created with the objective of trapping cylindrical flow for application in a Savonius VAWT. While stator assemblies have been studied in situ around Savonius rotors in the past, they have never been isolated from the rotor to determine the physics of the flow field, raising the likelihood that a moving rotor could cover up deficiencies attributable to the stator design. The flow field created by a stator assembly, sans rotor, is studied computationally using three-dimensional (3D) numerical simulations in the commercial computational fluid dynamics (CFD) package Star-CCM+. Examination of the velocity and pressure contours at the central stator plane shows that the maximum induced velocity exceeded the freestream velocity by 65%. However, flow is not sufficiently trapped in the stator assembly, with excess leakage occurring between the stator blades due to adverse pressure gradients and momentum loss from induced vorticity. A parametric study was conducted on the effect of the number of stator blades with simulations conducted with 6, 12, and 24 blades. Reducing the blade number resulted in a reduction in the cohesiveness of the internal swirling flow structure and increased the leakage of flow through the stator. Two unique energy loss mechanisms have been identified with both caused by adverse pressure gradients induced by the stator.
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April 2018
Technical Briefs
Trapped Cylindrical Flow With Multiple Inlets for Savonius Vertical Axis Wind Turbines
Aaron S. Alexander,
Aaron S. Alexander
Mem. ASME
Department of Engineering Technology,
Oklahoma State University,
567 Engineering North,
Stillwater, OK 74078
e-mail: aaron.s.alexander@okstate.edu
Department of Engineering Technology,
Oklahoma State University,
567 Engineering North,
Stillwater, OK 74078
e-mail: aaron.s.alexander@okstate.edu
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Arvind Santhanakrishnan
Arvind Santhanakrishnan
Department of Mechanical and Aerospace Engineering,
Oklahoma State University,
218 Engineering North,
Stillwater, OK 74078
e-mail: askrish@okstate.edu
Oklahoma State University,
218 Engineering North,
Stillwater, OK 74078
e-mail: askrish@okstate.edu
Search for other works by this author on:
Aaron S. Alexander
Mem. ASME
Department of Engineering Technology,
Oklahoma State University,
567 Engineering North,
Stillwater, OK 74078
e-mail: aaron.s.alexander@okstate.edu
Department of Engineering Technology,
Oklahoma State University,
567 Engineering North,
Stillwater, OK 74078
e-mail: aaron.s.alexander@okstate.edu
Arvind Santhanakrishnan
Department of Mechanical and Aerospace Engineering,
Oklahoma State University,
218 Engineering North,
Stillwater, OK 74078
e-mail: askrish@okstate.edu
Oklahoma State University,
218 Engineering North,
Stillwater, OK 74078
e-mail: askrish@okstate.edu
Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received February 25, 2017; final manuscript received September 22, 2017; published online December 4, 2017. Assoc. Editor: Matevz Dular.
J. Fluids Eng. Apr 2018, 140(4): 044501 (7 pages)
Published Online: December 4, 2017
Article history
Received:
February 25, 2017
Revised:
September 22, 2017
Citation
Alexander, A. S., and Santhanakrishnan, A. (December 4, 2017). "Trapped Cylindrical Flow With Multiple Inlets for Savonius Vertical Axis Wind Turbines." ASME. J. Fluids Eng. April 2018; 140(4): 044501. https://doi.org/10.1115/1.4038166
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