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Título : | Three-dimensional simulations of isobaric premixed flames freely propagating in narrow circular channels: breaking of symmetry |
Autor : | Dejoan, Anne Kurdyumov, Vadim |
Palabras clave : | symmetry breaking; premixed laminar flame; wall-heat losses; Lewis number; three-dimensional circular channel |
Fecha de publicación : | 2021 |
Editorial : | Combustion Theory and Modelling, Taylor and Francis |
Resumen : | In this work we perform three-dimensional simulations to study the breaking of sym-
metry of lean premixed isobaric flames propagating in narrow channels of circular
cross-section subject to an inlet Poiseuille flow. In particular we consider the effects
of the flow rate, the channel diameter, wall heat-losses for flames with the Lewis
number (Le) equal or less than unity.
Numerical analysis shows that for Le = 1 and under adiabatic conditions, a
supercritical bifurcation occurs at flow rates exceeding the critical value and the
axisymmetric flame becomes unstable, giving rise to a nonaxisymmetric flame. For
flames with Le < 1, a subcritical bifurcation occurs and we report multiplicity of
stable solutions: the flame can be axisymmetric and non-axisymmetric for the same
values of parameters. It is important to underline that both types of solutions are
stable, and thus can be observed experimentally. In the presence of wall heat-losses,
the critical flow rate corresponding to the bifurcation point increases. This indicates
a promoting effect of wall heat-losses on flame shape symmetry. We also find that
an extinction gap can appear when increasing the flow rate. For the smaller Lewis
number (Le = 0.5) we observe a complex flame dynamics, showing the coexistence
of steady and oscillatory combustion regimes. |
URI : | http://documenta.ciemat.es/handle/123456789/2120 |
Aparece en las colecciones: | Artículos de Energía
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