Aerodynamic characterization of isothermal swirling flows in combustors

Swirl flame stabilization is widespread among burners’ manufacturers, but the complex flow patterns are not yet fully understood. The interaction of two confined swirling jets leads to the formation of two recirculation zones being the flame located on the shear layer between the both zones. In such conditions, the lean mixtures can be burned producing low emissions. In the present study, flow structure and turbulent mixing of two isothermal coaxial jets are investigated using Large Eddy Simulation (LES). This is a challenging tool to achieve accuracy but it requests demanding spatial resolution and special treatment of results. By contrasting time-averaged radial profiles with experimental data of a classical benchmark, the model is validated. Results show that LES is able to reproduce the basic features of the flow pattern. Besides, the spectra analysis of instantaneous flow fields provides not only the energy decay but also the most energetic flow structures.

[1]  A. K. Oppenheim,et al.  Aerothermodynamic properties of stretched flames in enclosures , 1988 .

[2]  Derek Dunn-Rankin,et al.  Numerical and experimental study of “tulip” flame formation in a closed vessel , 1988 .

[3]  B. V. Johnson,et al.  Mass and momentum turbulent transport experiments with swirling confined coaxial jets. II , 1986 .

[4]  Abdul Waheed Badar,et al.  CFD based analysis of flow distribution in a coaxial vacuum tube solar collector with laminar flow conditions , 2012, International Journal of Energy and Environmental Engineering.

[5]  Anthony John Griffiths,et al.  Visualisation of isothermal large coherent structures in a swirl burner , 2009 .

[6]  R. Roback,et al.  Mass and Momentum Turbulent Transport. Experiments with Confined Swirling Coaxial Jets , 1984 .

[7]  C. Duwig,et al.  NEAR-FIELD DYNAMICS OF A TURBULENT ROUND JET WITH MODERATE SWIRL , 2008, Proceeding of Fifth International Symposium on Turbulence and Shear Flow Phenomena.

[8]  Christian Oliver Paschereit,et al.  Study of the Vortex Breakdown in a Conical Swirler Using LDV, LES and POD , 2007 .

[9]  S. Pope.  Turbulent Flows: FUNDAMENTALS , 2000 .

[10]  Laszlo Fuchs,et al.  A low-dissipative, scale-selective discretization scheme for the Navier–Stokes equations , 2012 .

[11]  K. Dinesh,et al.  Investigation of the influence of swirl on a confined coannular swirl jet , 2010 .

[12]  Karl W. Jenkins,et al.  Swirl effects on external intermittency in turbulent jets , 2012 .

[13]  Jochen Fröhlich,et al.  LES of a free annular swirling jet – Dependence of coherent structures on a pilot jet and the level of swirl , 2006 .

[14]  Marc A. Rosen,et al.  Review of underground coal gasification technologies and carbon capture , 2012 .

[15]  C. Duwig,et al.  Large eddy simulation of vortex breakdown/flame interaction , 2007 .

[16]  A. Savill,et al.  Large Eddy Simulation of a turbulent swirling coaxial jet , 2010 .

[17]  Luc Vervisch,et al.  DNS of a premixed turbulent V flame and LES of a ducted flame using a FSD-PDF subgrid scale closure with FPI-tabulated chemistry , 2005 .

[18]  David Littlejohn,et al.  Self-induced unstable behaviors of CH4 and H2/CH4 flames in a model combustor with a low-swirl injector , 2013 .

[19]  Lars Davidson.  HYBRID LES-RANS: INLET BOUNDARY CONDITIONS FOR FLOWS INCLUDING RECIRCULATION , 2007 .

[20]  H. Mohamed,et al.  Influence of turbulent mixing intensity on the MILD combustion and the pollutant formation , 2012 .

[21]  Suad Jakirlić,et al.  Experimental characterization and modelling of inflow conditions for a gas turbine swirl combustor , 2006 .