Experiments in Fluids

, Volume 12, Issue 3, pp 200–208 | Cite as

Blade manipulators in turbulent channel flow

  • B. Vasudevan
  • A. Prabhu
  • R. Narasimha


We report here the results of a series of careful experiments in turbulent channel flow, using various configurations of blade manipulators suggested as optimal in earlier boundary layer studies. The mass flow in the channel could be held constant to better than 0.1%, and the uncertainties in pressure loss measurements were less than 0.1 mm of water; it was therefore possible to make accurate estimates of the global effects of blade manipulation of a kind that are difficult in boundary layer flows. The flow was fully developed at the station where the blades were mounted, and always relaxed to the same state sufficiently far downstream. It is found that, for a given mass flow, the pressure drop to any station downstream is always higher in the manipulated than in the unmanipulated flow, demonstrating that none of the blade manipulators tried reduces net duct losses. However the net increase in duct losses is less than the drag of the blade even in laminar flow, showing that there is a net reduction in the total skin friction drag experienced by the duct, but this relief is only about 20% of the manipulator drag at most.


Boundary Layer Mass Flow Laminar Flow Skin Friction Pressure Loss 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

List of symbols

A, A′

log law constants


chord length of manipulator


drag of the manipulator


pressure gradient in the channel


half height of the channel


height of the channel (2h)


log law constant


length of the channel


leading edge of the manipulator


static pressure


static pressure at a location x on the channel


static pressure at the location x in the presence of manipulator


static pressure at any reference location x upstream of the manipulator


Reynolds number


thickness of the manipulator


trailing edge of the manipulator


velocity in the channel


friction velocity


average velocity in the channel


centre-line velocity in the channel


U/U *


velocities in the channel downstream of the manipulators


velocities in the channel at reference location upstream of the manipulators


Coles's wake function


width of channel


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  1. Acharya, M.; Escudier, M. P. 1983: Measurements of the wall shear stress in boundary layer flows. Proc. 4th Symp. Turbulent Shear Flows, pp. 277–286. Berlin Heidelberg New York: SpringerGoogle Scholar
  2. Anders, J. B.; Watson, R. D. 1985: Airfoil large eddy breakup devices for turbulent drag reduction. AIAA Paper 85-0520Google Scholar
  3. Bertelrud, A.; Truong, T. V.; Avellan, F. 1982: Drag reduction in turbulent boundary layers using ribbons. AIAA Paper 82-1370Google Scholar
  4. Bushnell, D. M. 1983: Turbulent drag reduction for external flows. AIAA Paper 83-0227Google Scholar
  5. Corke, T. C.; Nagib, H. M.; Guezennec, Y. G. 1979: Modifications in drag of turbulent boundary layers resulting from manipulation of large scale structure. In Viscous flow drag reduction, Prog. Astro. Aero. 72, 128–143Google Scholar
  6. Coustols, E.; Cousteix, J. 1986: Reduction of turbulent skin friction: Turbulence Moderators. 22nd AAAF Colloquium on Applied Aerodynamics, Lille, France, November 1985Google Scholar
  7. Dean, R. D. 1978: Reynolds number dependence of skin friction and other bulk flow variables in two-dimensional rectangular duct flow. J. Fluids Eng. 100, 215–223Google Scholar
  8. Govindaraju, S. P.; Chambers, F. W. 1987: Direct measurements of drag of ribbon-type manipulators in a turbulent boundary layer. AIAA J. 25, 388–394Google Scholar
  9. Hefner, J. N.; Weinstein, L. M.; Bushnell, D. M. 1980: Large eddy breakup scheme for turbulent viscous drag reduction. Prog. Astro. Aero. 72, 110–127Google Scholar
  10. Hefner, J. N.; Anders, J. B.; Bushnell, D. M. 1983: Alteration of outer flow structures for turbulent drag reduction. AIAA Paper 83-0293Google Scholar
  11. Luchik, T. S.; Tiederman, W. G. 1987: Timescale and structure of ejections and bursts in turbulent channel flows. J. Fluid Mech. 174, 529–552Google Scholar
  12. Mumford, J. C.; Savill, A. M. 1988: Manipulation of turbulent boundary layers by outer-layer devices. Skin friction and flow visualization results. J. Fluid Mech. 191, 389–418Google Scholar
  13. Nagib, H. M. 1983: A new view on origin, role and manipulation of large scales in turbulent boundary layers. NASA-CR-165861Google Scholar
  14. Narasimha, R.; Sreenivasan, K. R. 1985: The control of turbulent boundary layer flows. AIAA Paper 85-0519Google Scholar
  15. Narasimha, R.; Sreenivasan, K. R. 1988: Flat plate drag reduction by turbulence manipulation. Sadhana 12, 15–30Google Scholar
  16. Plesniak, M. W.; Nagib, H. M. 1985: Net drag reduction in turbulent boundary layers resulting from optimized manipulations. AIAA Paper 85-0518Google Scholar
  17. Poddar, K.; Van Atta, C. W. 1985: Turbulent boundary layer drag reduction on an axisymmetric body using LEBU manipulators. Proc. 5th Symposium on Turbulent Shear Flows, Cornell University, IthacaGoogle Scholar
  18. Poll, D. I. A.; Watson, R. D. 1984: On the relaxation of a turbulent boundary layer after an encounter with a forward facing step. In: Improvement of aerodynamic performance through boundary layer control and high lift system, AGARD Conf. Proc. 365, 18.1-10Google Scholar
  19. Pollard, A.; Savill, A. M.; Thomann, H. 1989: Turbulence pipe flow manipulation. J. Appl. Sci. Res. 46, 281–290Google Scholar
  20. Pollard, A.; Thomann, H.; Savill, A. M. 1990: Manipulation and modelling of turbulent pipe flow. Proc. 4th European Drag Reduction Meeting, Lausanne; July 1989. To be published by Kluwer Academic (Editor: E. Coustols)Google Scholar
  21. Prabhu, A.; Vasudevan, B.; Kailas Nath, P.; Kulkarni, R. S.; Narasimha, R. 1987: Blade manipulators in channel flows. In: Proc. IUTAM Symp. Turbulence Management & Relaminarization, Bangalore, pp 97–108. Berlin Heidelberg New York: SpringerGoogle Scholar
  22. Sahlin, A.; Johansson, A. V.; Alfredsson, P. H. 1988: The possibility of drag reduction by outer layer manipulators in turbulent boundary layers. Phys. Fluids 31, 2814–2820Google Scholar
  23. Takagi, S. 1983a: The structure of turbulent boundary layer controlled by the plates. Proc. 15th Turbulence Symp., TokyoGoogle Scholar
  24. Takagi, S. 1983b: On the mechanism of drag reduction in a turbulent boundary layer using a thin plate. Proc. 2nd Asian Congress Fluid Mech, p. 292. Beijing, China: Sciences PressGoogle Scholar
  25. Truong, T. V.; Bertelrud, A.; Veure, M. 1984: Boundary layer development of transverse ribbons. Abstracts, EUROMECH 181Google Scholar
  26. Wilkinson, S. P.; Anders, I B.; Lazos, B. S.; Bushnell, D. M. 1987: Turbulent drag research at NASA Langley -Progress and Plans. Presented at the Conference on “Turbulent drag reduction by passive means”. Royal Aeronautical Society, LondonGoogle Scholar
  27. Yajnik, K. S.; Acharya, M. 1987: Non-equilibrium effects in a turbulent boundary layer due to the destruction of large eddies. In: Structure and mechanisms of turbulence. Lecture Notes in Physics, 76, 249–260. New York: SpringerGoogle Scholar

Copyright information

© Springer-Verlag 1992

Authors and Affiliations

  • B. Vasudevan
    • 1
  • A. Prabhu
    • 1
  • R. Narasimha
    • 1
  1. 1.Department of Aerospace EngineeringIndian Institute of ScienceBangaloreIndia

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