TY - JOUR
T1 - Dynamics of an edge-flame in the corner region of two mutually perpendicular streams
AU - Kurdyumov, Vadim N.
AU - Matalon, Moshe
N1 - Funding Information:
This work has been partially supported by the National Science foundation under grant DMS-0405129. V.K. also acknowledges the support of the Spanish Government through the Ramón y Cajal Program and the MEC under Project ENE2005-09190-C4. M.M. also acknowledges the support of the United States Israel Binational Science Foundation under grant 2004069.
PY - 2007
Y1 - 2007
N2 - The stabilization and dynamics of an edge-flame in the corner region of two mutually perpendicular streams, one of fuel and the other of oxidizer, is studied within the context of a diffusive-thermal model, with an imposed flow satisfying the Navier-Stokes equations. The formulation allows for non-unity Lewis numbers and finite rate chemis'try with an Arrhenius dependence on temperature. Two flow configurations, corresponding to inlet velocity profiles of uniform speed and of constant strain, have been examined. The results identify the dependence of the flame standoff distance on the flow as well as on the properties of the mixture, including the Damköhler D and Lewis numbers. For high flow rates, or small enough D, sufficient pre-mixing occurs in front of the edge-flame, which consequently takes on a tribrachial structure consisting of two premixed branches, one lean and one rich, with a trailing diffusion flame sheet. For large D, however, there is no enough premixing and the chemical reaction occurs in a small kernel very close to the corner, much like a local thermal explosion; further downstream the reaction occurs along a diffusion flame sheet that extends along the symmetry axis. The present results also predict the onset of spontaneous oscillations when the Lewis numbers are sufficiently large provided the flow rate is sufficiently high, or D reduced below a critical value. Oscillations are first sustained when D is reduced below criticality, but depending on the flow conditions, they are either damped leading to flame re-stabilization, or amplified leading to blow-off.
AB - The stabilization and dynamics of an edge-flame in the corner region of two mutually perpendicular streams, one of fuel and the other of oxidizer, is studied within the context of a diffusive-thermal model, with an imposed flow satisfying the Navier-Stokes equations. The formulation allows for non-unity Lewis numbers and finite rate chemis'try with an Arrhenius dependence on temperature. Two flow configurations, corresponding to inlet velocity profiles of uniform speed and of constant strain, have been examined. The results identify the dependence of the flame standoff distance on the flow as well as on the properties of the mixture, including the Damköhler D and Lewis numbers. For high flow rates, or small enough D, sufficient pre-mixing occurs in front of the edge-flame, which consequently takes on a tribrachial structure consisting of two premixed branches, one lean and one rich, with a trailing diffusion flame sheet. For large D, however, there is no enough premixing and the chemical reaction occurs in a small kernel very close to the corner, much like a local thermal explosion; further downstream the reaction occurs along a diffusion flame sheet that extends along the symmetry axis. The present results also predict the onset of spontaneous oscillations when the Lewis numbers are sufficiently large provided the flow rate is sufficiently high, or D reduced below a critical value. Oscillations are first sustained when D is reduced below criticality, but depending on the flow conditions, they are either damped leading to flame re-stabilization, or amplified leading to blow-off.
KW - Blow-off
KW - Diffusion flame
KW - Diffusive-thermal
KW - Edge-flame
KW - Heat loss
KW - Instabilities
KW - Oscillations
KW - Restabilization
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U2 - 10.1016/j.proci.2006.07.250
DO - 10.1016/j.proci.2006.07.250
M3 - Conference article
AN - SCOPUS:34548719456
SN - 1540-7489
VL - 31 I
SP - 929
EP - 938
JO - Proceedings of the Combustion Institute
JF - Proceedings of the Combustion Institute
IS - 1
T2 - 31st International Symposium on Combustion
Y2 - 5 August 2006 through 11 August 2006
ER -