Skip to main content

Local linear stability analysis of cyclone separators

  • T. A. Grimble (a1), A. Agarwal (a1) and M. P. Juniper (a1)

Local linear stability analysis is applied to the flow inside a cyclone separator to investigate the unsteady precession of the vortex core. The results of the stability analysis are compared with experimental measurements of the vortex oscillations using high-speed photography with particle seeding and hot-wire anemometry. The experiments reveal distinct spatial variation in the oscillation behaviour within the cyclone. The unsteady motion is focused at each end of the device, at both the narrow cone tip and just below the exhaust duct at the top of the cone, which is known as a vortex finder. The local stability analysis shows that an absolute instability is present throughout the flow for some non-zero azimuthal wavenumbers. The unsteady flow is observed to be driven by coupling between the shear layer and inertial waves confined within the vortex core. Comparison of the stability analysis with experiments shows the same frequency and mode shape behaviour and suggests that the local analysis accurately predicts the unstable modes of the system. The precessing vortex core is responsible for a narrow-band acoustic noise. Comparisons are also drawn with acoustic measurements made on cyclones in which the system is defined by key non-dimensional parameters, such as the swirl number and outlet diameter ratio. The results in this study demonstrate the applicability of local stability analysis to a complex swirling system and yield credible details about the underlying mechanisms of the unstable flow inside the cyclone.

Corresponding author
Email address for correspondence:
Hide All
ANSYS2011 FLUENT Theory Guide Release 14.0.
Bers A. 1983 Space–time evolution of plasma instabilities – absolute and convective. In Basic Plasma Physics (ed. Galeev A. A. & Sudan R. N.), vol. 1. Elsevier.
Chanaud R. C. 1965 Observations of oscillatory motion in certain swirling flows. J. Fluid Mech. 21, 111127.
Cortes C. & Gil A. 2007 Modeling the gas and particle flow inside cyclone separators. Prog. Energy Combust. Sci. 33 (5), 409452.
Derksen J. J. & Van den Akker H. E. A. 2000 Simulation of vortex core precession in a reverse-flow cyclone. AIChE J. 46 (7), 13171331.
Gallaire F. & Chomaz J.-M. 2003 Instability mechanisms in swirling flows. Phys. Fluids 15, 26222639.
Gimbun J., Chuah T. G., Choong T. S. Y. & Fakhru’l-Razi A. 2005 A CFD study on the prediction of cyclone collection efficiency. Intl J. Comput. Meth. Engng Sci. Mech. 6 (3), 161168.
Grimble T. A. & Agarwal A. 2015 Characterisation of acoustically linked oscillations in cyclone separators. J. Fluid Mech. 780, 4559.
Gronald G. & Derksen J. J. 2011 Simulating turbulent swirling flow in a gas cyclone: a comparison of various modeling approaches. Powder Technol. 205, 160171.
Gupta A. K., Lilley D. G. & Syred N. 1984 Swirl Flows. Abaqus Press.
Hoekstra A. J., Derksen J. J. & Van Den Akker H. E. A. 1999 An experimental and numerical study of turbulent swirling flow in gas cyclones. Chem. Engng Sci. 54, 20552065.
Huerre P. 2000 Open shear flow instabilities. In Perspectives in Fluid Dynamics (ed. Batchelor G. K., Moffatt H. K. & Worster M. G.), pp. 159229. Cambridge University Press.
Huerre P. & Monkewitz P. A. 1990 Local and global instabilities in spatially developing flows. Annu. Rev. Fluid Mech. (22), 473537.
Juniper M. P.2012 Absolute and convective instability in gas turbine fuel injectors. Proceedings of ASME Turbo Expo 2012: Power for Land, Sea and Air.
Juniper M. P., Tammisola O. & Lundell F. 2011 The local and global stability of confined planar wakes at intermediate Reynolds number. J. Fluid Mech. 686, 218238.
Loiseleux T., Chomaz J. M. & Huerre P. 1998 The effect of swirl on jets and wakes: linear instability of the Rankine vortex with axial flow. Phys. Fluids 10 (5), 11201134.
Meliga P., Pujals G. & Serre E. 2012 Sensitivity of 2-D turbulent flow past a D-shaped cylinder using global stability. Phys. Fluids 24, 061701.
Mettot C., Sipp D. & Bézard H. 2014 Quasi-laminar stability and sensitivity analyses for turbulent flows: prediction of low-frequency unsteadiness and passive control. Phys. Fluids 26, 045112.
Oberleithner K., Sieber M., Nayeri C. N., Paschereit C. O., Petz C., Hege H.-C., Noack B. R. & Wygnanski I. 2011 Three-dimensional coherent structures in a swirling jet undergoing vortex breakdown: stability analysis and empirical mode construction. J. Fluid Mech. 679, 383414.
Peng W., Hoffmann A. C., Dries H. W. A., Regelink M. A. & Stein L. E. 2005 Experimental study of the vortex end in centrifugal separators: the nature of the vortex end. Chem. Engng Sci. 60, 69196928.
Pier B. 2008 Local and global instabilities in the wake of a sphere. J. Fluid Mech. 603, 3961.
Pisarev G. I., Gjerde V., Balakin B. V., Hoffmann A. C., Dijkstra H. A. & Peng W. 2012 Experimental and computational study of the end of the vortex phenomenon in reverse-flow centrifugal separators. AIChE J. 58, 13711380.
Qadri U. A., Mistry D. & Juniper M. P. 2013 Structural sensitivity of spiral vortex breakdown. J. Fluid Mech. 720, 558581.
Rayleigh Lord 1916 On the dynamics of revolving fluids. Proc. R. Soc. Lond. 93 (648), 148154.
Reynolds W. C. & Hussain A. K. M. F. 1972 The mechanics of an organized wave in turbulent shear flow. Part 3. Theoretical models and comparisons with experiments. J. Fluid Mech. 54, 263288.
Saffman P. G. 1992 Vortex Dynamics. Cambridge University Press.
Saric W. S. 1994 Görtler vortices. Annu. Rev. Fluid Mech. 26, 379409.
Slack M. D., Prasad R. O., Bakker A. & Boysan F. 2000 Advances in cyclone modelling using unstructured grids. Chem. Engng Res. Des. 78, 10981104.
Syred N. 2006 A review of oscillation mechanisms and the role of the precessing vortex core (PVC) in swirl combustion systems. Prog. Energy Combust. Sci. 32, 93161.
Tammisola O.2011 Numerical stability studies of one-phase and immiscible two-phase jets and wakes. PhD thesis, KTH, Sweden.
Tammisola O. & Juniper M. P. 2016 Coherent structures in a swirl injector at Re = 4800 by nonlinear simulations and linear global modes. J. Fluid Mech. 792, 620657.
Turton S. E., Tuckerman L. & Barkley D. 2015 Prediction of frequencies in thermosolutal convection from mean flows. Phys. Rev. E 91, 043009.
Yazdabadi P. A, Griffiths A. J. & Syred N. 1994a Characterization of the PVC phenomena in the exhaust of a cyclone dust separator. Exp. Fluids 17, 8495.
Yazdabadi P. A., Griffiths A. J. & Syred N. 1994b Investigations into the precessing vortex core phenomenon in cyclone dust separators. Proc. Inst. Mech. Engrs E 208, 147154.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Journal of Fluid Mechanics
  • ISSN: 0022-1120
  • EISSN: 1469-7645
  • URL: /core/journals/journal-of-fluid-mechanics
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 3
Total number of PDF views: 155 *
Loading metrics...

Abstract views

Total abstract views: 291 *
Loading metrics...

* Views captured on Cambridge Core between 8th March 2017 - 16th December 2017. This data will be updated every 24 hours.