Hostname: page-component-cd9895bd7-gvvz8 Total loading time: 0 Render date: 2024-12-28T07:03:27.735Z Has data issue: false hasContentIssue false
  • English
  • Français

Active vorticity control in a shear flow using a flapping foil

Published online by Cambridge University Press:  26 April 2006

R. Gopalkrishnan ,
M. S. Triantafyllou ,
G. S. Triantafyllou  and
D. Barrett
R. Gopalkrishnan
Affiliation:
Department of Ocean Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
M. S. Triantafyllou
Affiliation:
Department of Ocean Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
G. S. Triantafyllou
Affiliation:
The Levich Institute and Department of Mechanical Engineering, The City College of New York, New York, NY 10031, USA
D. Barrett
Affiliation:
Department of Ocean Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Get access Rights & Permissions [Opens in a new window]

Abstract

It is shown experimentally that free shear flows can be substantially altered through direct control of the large coherent vortices present in the flow.

First, flow-visualization experiments are conducted in Kalliroscope fluid at Reynolds number 550. A foil is placed in the wake of a D-section cylinder, sufficiently far behind the cylinder so that it does not interfere with the vortex formation process. The foil performs a heaving and pitching oscillation at a frequency close to the Strouhal frequency of the cylinder, while cylinder and foil also move forward at constant speed. By varying the phase of the foil oscillation, three basic interaction modes are identified. (i) Formation of a street of pairs of counter-rotating vortices, each pair consisting of one vortex from the initial street of the cylinder and one vortex shed by the foil. The width of the wake is then substantially increased. (ii) Formation of a street of vortices with reduced or even reverse circulation compared to that of oncoming cylinder vortices, through repositioning of cylinder vortices by the foil and interaction with vorticity of the opposite sign shed from the trailing edge of the foil. (iii) Formation of a street of vortices with circulation increased through merging of cylinder vortices with vortices of the same sign shed by the foil. In modes (ii) and (iii) considerable repositioning of the cylinder vortices takes place immediately behind the foil, resulting in a regular or reverse Kármán street. The formation of these three interaction patterns is achieved only for specific parametric values; for different values of the parameters no dominant stable pattern emerges.

Subsequently, the experiments are repeated in a different facility at larger scale, resulting in Reynolds number 20000, in order to obtain force and torque measurements. The purpose of the second set of experiments is to assess the impact of flow control on the efficiency of the oscillating foil, and hence investigate the possibility of energy extraction. It is found that the efficiency of the foil depends strongly on the phase difference between the oscillation of the foil and the arrival of cylinder vortices. Peaks in foil efficiency are associated with the formation of a street of weakened vortices and energy extraction by the foil from the vortices of the vortex street.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 274 , 10 September 1994 , pp. 1 - 21
Copyright
© 1994 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Aref, H. 1983 Integrable, chaotic, and turbulent vortex motion in two dimensional flows. Ann. Rev. Fluid Mech. 15, 345–389.Google Scholar
Aref, H. & Siggia, E. D. 1981 Evolution and breakdown of a vortex street in two-dimensional flows. J. Fluid Mech. 109, 435–463.Google Scholar
Chen, Y. Y. & Templin, J. T. 1974 Suppression of spatial waves by distortion of jet velocity profile. Phys. Fluids 17 (11), 2124–2125.Google Scholar
Corke, T. C., Guezennec, Y. G. & Nagib, H. M. 1979 Modification in drag of turbulent boundary layers resulting from manipulation of large-scale structures. In Proc. Viscous Drag Reduction Symp. Dallas. AIAA Prog. Astro. Aero. 72, 128–143.
Coutanceau, M. & Defaye, J. R. 1991 Circular cylinder wake configurations: A flow visualization survey, Appl. Mech. Rev. 44, 255–305.Google Scholar
Doi, J. 1989 Agriculture. In Handbook of flow visualization (ed. W. J. Yang), pp. 629–631. Hemisphere.
Dowling, A. P. 1985 The effect of large-eddy breakup devices on oncoming vorticity. J. Fluid Mech. 160, 447–463.Google Scholar
Ffowcs Williams, J. E., & Zhao, B. C. 1989 The active control of vortex shedding. J. Fluids Struct. 3, 115–122.Google Scholar
Freymuth, P. 1990 Thrust generation by an airfoil in hover modes. Exps Fluids 9, 17–24.Google Scholar
Gopalkrishnan, R. 1993 Vortex-induced forces on oscillating bluff cylinders. PhD thesis, Massachusetts Institute of Technology, Cambridge, MA.
Gorman, M. & Swinney, H. C. 1982 Spatial and temporal characteristics of modulated waves in the circular Couette system. J. Fluid Mech. 117, 117–123.Google Scholar
Hefner, J. N., Weinstein, L. M. & Bushnell, D. M. 1979 Large-eddy break-up scheme for turbulent viscous drag reduction. In Proc. Viscous Drag Reduction Symp. Dallas. AIAA Prog. Astro. Aero. 72, 110–127.Google Scholar
Hoerner, S. F. 1965 Fluid Dynamic Drag. Published by the author.
Katzmayr, R. 1922 Effect of periodic changes of angle of attack on behavior of airfoils. NACA TM-147.Google Scholar
Koochesfahani, M. M. & Dimotakis, P. E. 1988 A cancellation experiment in a forced turbulent shear layer. AIAA 88–3713-CP.Google Scholar
Matisse, P. & Gorman, M. 1984 Neutrally buoyant anisotropic particles for flow visualization. Phys. Fluids 27 (4), 759–760.Google Scholar
Ongoren, A. & Rockwell, D. 1988 Flow structure form of an oscillating cylinder. Part 1. Mechanisms of phase shift and recovery in the near wake. J. Fluid Mech. 191, 197–223.Google Scholar
Rosen, M. W. 1959 Water flow about a swimming fish. Stat. Tech. Publ. US Naval Ordn. Test Station, California, NOTS TP 2298.
Roussopoulos, K. 1993 Feedback control of vortex shedding at low Reynolds numbers. J. Fluid Mech. 248, 267–296.Google Scholar
Savaş, O. 1985 On flow visualization using reflecting flakes. J. Fluid Mech. 152, 235–248.Google Scholar
Schmidt, W. 1965 Der wellpropeller, ein neuer antrieb fur wasser-, land- und luftfahrzeuge. Z. Flugwiss. 13, 472–479.Google Scholar
Strykowski, P. J. & Sreenivasan, K. R. 1990 On the formation and suppression of vortex shedding at low Reynolds numbers. J. Fluid Mech. 218, 71–107.Google Scholar
Tokumaru, P. T. & Dimotakis, P. E. 1991 Rotary oscillation control of a cylinder wake. J. Fluid Mech. 224, 77–90.Google Scholar
Triantafyllou, G. S., Triantafyllou, M. S. & Grosenbaugh, M. A. 1993 Optimal thrust development in oscillating foils with application to fish propulsion. J. Fluids Struct. 7, 205–224.Google Scholar
Triantafyllou, M. S., Triantafyllou, G. S. & Gopalkrishnan, R. 1991 Wake mechanics for thrust generation in oscillating foils. Phys. Fluidsd A 3 (12), 2835–2837.Google Scholar
Williamson, C. H. K. & Roshko, A. 1988 Vortex formation in the wake of an oscillating cylinder. J. Fluids Struct. 2, 155–381.Google Scholar
Zdravkovich, M. M. 1981 Review and classification of various aerodynamic and hydrodynamic means for suppressing vortex shedding. J. Wind Engng Indust. Aero. 7, 145–189.Google Scholar