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oai:oa.upm.es:1295
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A bifurcation analysis of high-temperature ignition of H2-O2 diffusion flames
Sánchez Pérez, Antonio Luis
Liñán Martínez, Amable
Williams, F.A.
Physics
Aeronautics
The form of the ignition branch for steady, counterflow, hydrogen-oxygen diffusion flames, with dilution
permitted in both streams, is investigated for two-step reduced chemistry by methods of bifurcation theory.
Attention is restricted to fuel-stream temperatures less than or equal to the oxidizer-stream temperature
Tx and to T„ larger than or of the order of the crossover temperature Tc at which the rates of production
and consumption of H atoms are equal. Two types of solutions are identified, a frozen solution that always
exists in this kinetic approximation because all rates are proportional to the concentration of the intermedíate
H atom, and an ignited solution, represented by a branch of the curve giving the máximum H
concentration in terms of a Damkohler number constructed from the strain rate and the rate of the
branching step H + Os - OH + O. For T„ > T„ the latter bifurcates from the frozen solution if the
Damkohler number is increased to a critical valué. For T„ larger than a valué Ts > Tc, the effeets of
chemical heat reléase are small, and ignition is always gradual in the sense that the limiting ignited-branch
slope is positive (supercritical bifurcation) and there is no S curve. For T„ in the range Tc< T„ < T„ the
heat reléase associated with the radical-consumption step causes the limiting ignition-branch slope to
become negative (subcritical bifurcation), producing abrupt ignition which leads to an S curve. For valúes
of Tx below crossover, the ignited branch appears as a C-shaped curve unconnected to the frozen solution.
The method of analysis introduced here offers a first step toward analytical description of nonpremixed
H2-02 autoignition.
E.T.S.I. Aeronáuticos (UPM)
http://creativecommons.org/licenses/by-nc-nd/3.0/es/
1994
info:eu-repo/semantics/conferenceObject
Presentation at Congress or Conference
Twenty-Fifth Symposium (International) on Combustion | Symposium (International) on Combustion (25. 1994. Irvine, California) | 31 Jul - 5 Ago 1994 | Irvine, California
PeerReviewed
application/pdf
spa
info:eu-repo/semantics/openAccess
http://oa.upm.es/1295/