Hostname: page-component-745bb68f8f-cphqk Total loading time: 0 Render date: 2025-01-09T21:56:01.283Z Has data issue: false hasContentIssue false
  • English
  • Français

The effect of buoyancy on vortex breakdown in a swirling jet

Published online by Cambridge University Press:  04 January 2007

DINA MOURTAZIN  and
JACOB COHEN
DINA MOURTAZIN
Affiliation:
Faculty of Aerospace Engineering, Technion – IIT, Haifa, 32000, Israel
JACOB COHEN
Affiliation:
Faculty of Aerospace Engineering, Technion – IIT, Haifa, 32000, Israel
Get access Rights & Permissions [Opens in a new window]

Abstract

The purpose of this experimental study is to explore the effect of buoyancy on vortex breakdown (VB) in swirling jets. Three non-dimensional parameters govern the flow: the jet exit Reynolds number, the swirl ratio and the Richardson number (buoyancy). The experimental apparatus consists of a vertical swirling water jet which discharges into a large tank. Moderate values of the Reynolds number are used, in the range 150 ≤ Re ≤ 600. Swirl is imparted to the jet in a rotating chamber whereas the temperature difference between the jet and its surroundings is established by passing the jet through a heat exchanger, immersed in a circulating water bath with a controlled temperature. Vector maps of the vertical mid-plane and horizontal cross-sections are obtained by particle image velocimetry (PIV) measurements. It is demonstrated that VB can be effectively suppressed (enhanced) when there is a negative (positive) temperature difference between the jet core and its surrounding fluid. The experimental critical swirl ratio for the appearance of VB is found to be in good agreement with a simple criterion, originally derived by Billant, Chomaz & Huerre (J. Fluid Mech., vol. 376, 1998, p. 183) for isothermal swirling jets and extended here to include buoyancy effects. The transition of VB from a closed bubble to an open cone configuration is mapped in terms of the Reynolds and Richardson numbers. Finally, the effect of the upstream velocity field on the critical rotation rate for the onset of VB and its configuration is exhibited using two different interchangeable rotating chambers.

Type
Papers
Information
Journal of Fluid Mechanics , Volume 571 , 25 January 2007 , pp. 177 - 189
Copyright
Copyright © Cambridge University Press 2007

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

REFERENCES

Arkadyev, A., Bar-Yoseph, P., Solan, A. & Roesner, K. 1993 Thermal effects on axisymmetric vortex breakdown in a spherical gap. Phys. Fluids A 5, 1211.CrossRefGoogle Scholar
Billant, P., Chomaz, J. M. & Huerre, P. 1998 Experimental study of vortex breakdown in swirling jets. J. Fluid Mech. 376, 183 (referred to herein as BCH).CrossRefGoogle Scholar
Escudier, M. P. & Keller, J. J. 1983 Vortex breakdown: a two-stage transition. Aerodynamics of Vortical Flows in Three Dimensions. AGARD CP-342 (ref 25).Google Scholar
Gallaire, F. & Chomaz, J. M. 2003a Instability mechanisms in swirling flows. Phys. Fluids 15, 2622.CrossRefGoogle Scholar
Gallaire, F. & Chomaz, J. M. 2003b Mode selection on in swirling jet experiments: a linear stability analysis. J. Fluid Mech. 494, 223.CrossRefGoogle Scholar
Gallaire, F., Rott, S. & Chomaz, J. M. 2004 Experimental study of a free and forced swirling jet. Phys. Fluids 16, 2907.CrossRefGoogle Scholar
Gallaire, F., Ruith, M., Meiburg, E., Chomaz, J. M. & Huerre, P. 2006 Spiral vortex breakdown as a global mode. J. Fluid Mech. 549, 71.CrossRefGoogle Scholar
Herrada, M. A. & Shtern, V. 2003a Control of vortex breakdown by temperature gradient. Phys. Fluids 15, 3468.CrossRefGoogle Scholar
Herrada, M. A. & Shtern, V. 2003b Vortex breakdown control by adding near-axis swirl and temperature gradients. Phys. Rev. E 68, 041202–1.CrossRefGoogle ScholarPubMed
Ivanic, T., Foucault, E. & Pecheux, J. 2003 Dynamics of swirling jet flows. Exps. Fluids 35, 317.Google Scholar
Kim, W. N. & Hyun, J. M. 1997 Convective heat transfer in a cylinder with a rotating lid under stable stratification. Intl J. Heat Fluid Flow 18, 384.Google Scholar
Lee, C. H. & Hyun, J. M. 1999 Flow of a stratified fluid in a cylinder with a rotating lid. Intl J. Heat Fluid Flow 20, 26.CrossRefGoogle Scholar
Liang, H. & Maxworthy, T. 2005 An experimental investigation of swirling jets. J. Fluid Mech. 525, 115.CrossRefGoogle Scholar
Lim, D. W. & Redekopp, L. G. 1998 Absolute instability conditions for variable density, swirling jet flows. Eur. J. Mech. B/Fluids 17, 165.CrossRefGoogle Scholar
Loiseleux, T. & Chomaz, J. M. 2002 Breaking of rotational symmetry in a swirling jet experiment. Phys. Fluids 15, 511.CrossRefGoogle Scholar
Loiseleux, T., Delbende, I. & Huerre, P. 2000 Absolute and convective instabilities of a swirling jet/wake shear layer. Phys. Fluids 12, 375.CrossRefGoogle Scholar
Lugt, H. J. & Abboud, M. 1987 Axisymmetrical vortex breakdown with and without temperature effects in a container with a rotating lid. J. Fluid Mech. 179, 179.CrossRefGoogle Scholar
Martin, J. A & Meiburg, E. 1994 On the stability of swirling jet shear layer. Phys. Fluids 6, 424.CrossRefGoogle Scholar
Ruith, M. R., Chen, P., Meiburg, E. & Maxworthy, T. 2003 Three-dimensional vortex breakdown in swirling jets and wakes: direct numerical simulation. J. Fluid Mech. 486, 331.CrossRefGoogle Scholar
Shtern, V., Hussain, F. & Herrada, M. 2000 New features of swirling jets. Phys. Fluids 12, 2868.CrossRefGoogle Scholar
Sun, D. J., Hu, G. H., Gao, Z. & Yin, X. Y. 2002 Stability and temporal evolution of a swirling jet with centrifugal unstable azimuthal velocity. Phys. Fluids 14, 4081.CrossRefGoogle Scholar
Wang, S. & Rusak, Z. 1977 The dynamics of a swirling flow in a pipe and transition to axisymmetric vortex breakdown. J. Fluid Mech. 340, 177.CrossRefGoogle Scholar