Experiments in Fluids

, 57:141 | Cite as

Transient wall-jet flowing over a circular cylinder

Research Article
  • 381 Downloads

Abstract

The transient flow of a two-dimensional wall-jet over a circular cylinder, following rapid initiation and termination, was investigated experimentally. Unsteady surface pressures and unsteady pressure-sensitive paint were used to gain a basic understanding of the flow physics. Jet initiation produced a starting vortex, upstream of which the Coandă flow developed, producing a large low-pressure peak. Immediately following jet termination, the pressure increased over the first quarter of the circumference, while the downstream separation region remained virtually unaffected. Simplifying analyses and dimensional arguments were used to show that the timescales characterizing the transient development of the integrated loads depend only on the square of the slot height and the kinematic viscosity and are thus independent of the jet velocity. Following jet initiation, the resulting loads varied according to a linear transient model, while small nonlinearities were observed following jet termination. Unsteady pressure-sensitive paint showed that the starting jet emerges from the slot in a two-dimensional manner and that streamwise streaks, identified as Görtler vortices, form well before the flow reaches steady state. During termination, the streamwise structures dissipate downstream initially, with the dissipation propagating upstream.

Keywords

Shear Layer Streamwise Vortex Slot Width Separation Angle Momentum Coefficient 
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.

Abbreviations

b

Span of the cylinder

Cp

Pressure coefficient (p  − p)R/(p 0 − p )h

CR

Resultant force coefficient, \(F_{\text{R}} /\rho U_{j,\text{max} }^{2} R\)

\(C_{\mu } (t)\)

Momentum coefficient, \(h/R(U_{j} (t)/U_{j,\text{max} } )^{2}\)

D

Cylinder diameter

FN

Force per unit span, normal to the jet slot

FT

Force per unit span, tangential to the jet slot

FR

Resultant force on the cylinder

h

Slot width

p

Surface pressure

p0

Stagnation pressure

p

Ambient pressure

Q

Jet volumetric flowrate

R

Cylinder radius

Re

Reynolds number \(\sqrt {\left( {p_{0} - p_{\infty } } \right)hR /\rho \nu^{2}}\)

t

Time

ti, tt

Jet initiation, termination times

Uj

Jet velocity

θ

Azimuthal angle measured from the slot

θs

Flow separation angle measured from the slot

τ

Time constant

Notes

Acknowledgments

The authors acknowledge the support from the Grand Technion Energy Program (GTEP). JWG gratefully acknowledges the support of a Fulbright Global Scholar Award from the U.S. Department of State, administered by the United States-Israel Educational Foundation.

References

  1. Allen D, Smith BL (2009) Axisymmetric Coanda-assisted vectoring. Exp Fluids 46:55–64CrossRefGoogle Scholar
  2. Amitay M, Smith BL, Glezer A (1998) Aerodynamic flow control using synthetic jet technology. In: AIAA paper, p 208Google Scholar
  3. Coanda H (1936) Device for deflecting a stream of elastic fluid projected into an elastic fluid. US Patent No. 2,052,869. 1 Sept 1936Google Scholar
  4. Dumas A, Subhash M, Trancossi M, Marques JP (2014) The influence of surface temperature on Coanda effect. Energy Procedia 45:626–634CrossRefGoogle Scholar
  5. Erath BD, Plesniak MW (2010) An investigation of asymmetric flow features in a scaled-up driven model of the human vocal folds. Exp Fluids 49(1):131–146CrossRefGoogle Scholar
  6. Fekete GI (1963) Coanda flow of a two-dimensional wall jet on the outside of a cylinder. Rep. 63-11. McGill University, Department of Mechanical Engineering, MontréalGoogle Scholar
  7. Floryan JM, Saric WS (1982) Stability of Gortler vortices in boundary layers. AIAA J 20(3):316–324MathSciNetCrossRefMATHGoogle Scholar
  8. French JW, Guntheroth WG (1970) An explanation of asymmetric upper extremity blood pressures in supravalvular aortic stenosis the Coanda effect. Circulation 42(1):31–36CrossRefGoogle Scholar
  9. Fujisawa N, Kobayashi R (1987) Turbulence characteristics of wall jets along strong convex surfaces. J Mech Sci 29:311–320CrossRefGoogle Scholar
  10. Gammack PD, Dyson J, Smith AG, Brough IJ, Teyu MS, Salleh NM (2015) Fan having a magnetically attached remote control. US Patent No. 9,004,878. 14 Apr 2015Google Scholar
  11. Geropp D, Odenthal H-J (2000) Drag reduction of motor vehicles by active flow control using the Coanda effect. Exp Fluids 28(1):74–85CrossRefGoogle Scholar
  12. Greenblatt D, Neuburger D, Wygnanski I (2001) Dynamic stall control by intermittent periodic excitation. AIAA J Aircr 38(1):188–190CrossRefGoogle Scholar
  13. Gregory JW, Sakaue H, Liu T, Sullivan JP (2014) Fast pressure-sensitive paint for flow and acoustic diagnostics. Ann Rev Fluid Mech 46:303–330MathSciNetCrossRefMATHGoogle Scholar
  14. Guitton DE (1964) Two-dimensional turbulent wall jets over curved surfaces. Rep. 64-7. McGill University, Department of Mechanical Engineering, MontréalGoogle Scholar
  15. Guitton DE, Newman BG (1977) Self-preserving turbulent wall jets over convex surfaces. J Fluid Mech 81(01):155–185CrossRefGoogle Scholar
  16. Han G, de Zhou M, Wygnanski I (2006) On streamwise vortices and their role in the development of a curved wall jet. Phys Fluids 18(9):095104. doi: 10.1063/1.2353403 CrossRefGoogle Scholar
  17. Jones GS, Englar RJ (2003) Advances in pneumatic-controlled high-lift systems through pulsed blowing. In: AIAA paper No. 2003-3411, 21st applied aerodynamics conference. Orlando, FloridaGoogle Scholar
  18. Likhachev O, Neuendorf R, Wygnanski I (2001) On streamwise vortices in a turbulent wall jet that flows over a convex surface. Phys Fluids 13(6):1822–1825CrossRefMATHGoogle Scholar
  19. Lo KP, Elkins CJ, Eaton JK (2012) Separation control in a conical diffuser with an annular inlet: center body wake separation. Exp Fluids 53(5):1317–1326CrossRefGoogle Scholar
  20. Miozzi M, Lalli F, Romano GP (2010) Experimental investigation of a free-surface turbulent jet with Coanda effect. Exp Fluids 49(1):341–353CrossRefGoogle Scholar
  21. Moss EA (1991) Laminar pipe flows accelerated from rest. N&O J 7–14Google Scholar
  22. Müller-Vahl H, Nayeri CN, Paschereit CO, Greenblatt D (2016) Dynamic stall control via adaptive blowing. Renew Energy 97:47–64CrossRefGoogle Scholar
  23. Naim A, Greenblatt D, Seifert A, Wygnanski I (2007) Active control of a circular cylinder flow at transitional Reynolds numbers. Flow Turbul Combust 78(3–4):383–407CrossRefGoogle Scholar
  24. Neuendorf R, Wygnanski I (1999) On a turbulent wall jet flowing over a circular cylinder. J Fluid Mech 381:1–25MathSciNetCrossRefMATHGoogle Scholar
  25. Neuendorf R, Lourenco L, Wygnanski I (2004) On large streamwise structures in a wall jet flowing over a circular cylinder. Phys Fluids 16(7):2158–2169CrossRefMATHGoogle Scholar
  26. Newman BG (1961) The deflection of plane jets by adjacent boundaries—Coanda effect. Bound Layer Flow Control 1:232–264Google Scholar
  27. Rayleigh L (1917) On the dynamics of revolving fluids. Proc R Soc Lond A Contain Pap Math Phys Character 93:148–154CrossRefMATHGoogle Scholar
  28. Reynolds O (1870) On the suspension of a ball by a jet of water. Taylor and Francis, LondonGoogle Scholar
  29. Saric WS (1994) Görtler vortices. Ann Rev Fluid Mech 26(1):379–409MathSciNetCrossRefMATHGoogle Scholar
  30. Tesař V, Bandalusena HCH (2011) Bistable diverter valve in microfluidics. Exp Fluids 50(5):1225–1233CrossRefGoogle Scholar
  31. Wille R, Fernholz H (1965) Report on the first European Mechanics Colloquium, on the Coanda effect. J Fluid Mech 23(4):801–819CrossRefGoogle Scholar
  32. Yao C, Chen FJ, Neuhart D (2006) Synthetic jet flowfield database for computational fluid dynamics validation. AIAA J 44(12):3153–3157CrossRefGoogle Scholar
  33. Young T (1800) Outlines of experiments and inquiries respecting sound and light. Proc R Soc Lond 1800–1814 1:8–10Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • Ron Danon
    • 1
  • James W. Gregory
    • 2
  • David Greenblatt
    • 1
  1. 1.Faculty of Mechanical EngineeringTechnion – Israel Institute of TechnologyHaifaIsrael
  2. 2.Department of Mechanical and Aerospace EngineeringThe Ohio State UniversityColumbusUSA

Personalised recommendations