An experimental study on flow separation control of hydrofoils with leading-edge tubercles at low Reynolds number

An experimental study on flow separation control of hydrofoils with leading-edge tubercles at low... Hydrodynamic characteristics of hydrofoils with leading-edge tubercles were experimentally investigated in a water tunnel at a Reynolds number of Re=1.4×104. Particle image velocimetry measurements and particle-streak visualizations reveal that the tubercles improve flow separation behaviour. In particular, hydrofoils with larger wave amplitudes and smaller wavelengths tend to perform significantly better in flow separation control. Cross-stream flow measurements indicate that streamwise counter-rotating vortex pairs are generated over the tubercles and mitigate flow separation. Analysis confirms that the tubercles function as vortex generators, due to their comparable heights relative to the boundary layer thickness. The vortex pairs meander and interact with adjacent flows, causing the flow separation behaviour to be occasionally unstable, thus leading to variable flow separation region sizes. This suggests that measures may have to be taken to ensure the stability of the counter-rotating vortex pairs for more persistent and predictable improvements. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Ocean Engineering Elsevier

An experimental study on flow separation control of hydrofoils with leading-edge tubercles at low Reynolds number

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Publisher
Elsevier
Copyright
Copyright © 2015 Elsevier Ltd
ISSN
0029-8018
eISSN
1873-5258
D.O.I.
10.1016/j.oceaneng.2015.08.004
Publisher site
See Article on Publisher Site

Abstract

Hydrodynamic characteristics of hydrofoils with leading-edge tubercles were experimentally investigated in a water tunnel at a Reynolds number of Re=1.4×104. Particle image velocimetry measurements and particle-streak visualizations reveal that the tubercles improve flow separation behaviour. In particular, hydrofoils with larger wave amplitudes and smaller wavelengths tend to perform significantly better in flow separation control. Cross-stream flow measurements indicate that streamwise counter-rotating vortex pairs are generated over the tubercles and mitigate flow separation. Analysis confirms that the tubercles function as vortex generators, due to their comparable heights relative to the boundary layer thickness. The vortex pairs meander and interact with adjacent flows, causing the flow separation behaviour to be occasionally unstable, thus leading to variable flow separation region sizes. This suggests that measures may have to be taken to ensure the stability of the counter-rotating vortex pairs for more persistent and predictable improvements.

Journal

Ocean EngineeringElsevier

Published: Nov 1, 2015

References

  • Passive and active flow control by swimming fishes and mammals
    Fish, F.E.; Lauder, G.V.
  • Leading-edge tubercles delay stall on humpback whale (megaptera novaeangliae) flippers
    Miklosovic, D.S.; Murray, M.M.; Howle, L.E.; Fish, F.E.
  • Influence of nozzle sharpness on the flow fields of V-notched nozzle jets
    New, T.H.; Tsovolos, D.
  • On the characteristics of minor-plane inclined elliptic jets
    New, T.H.; Tsovolos, D.
  • Control of vortical structures on a flapping wing via a sinusoidal leading-edge
    Ozen, C.A.; Rockwell, D.
  • Flapping dynamics of a low aspect-ratio energy-harvesting membrane immersed in a square cylinder wake
    Shi, Shengxian; New, T.H.; Liu, Yingzheng

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