TY - JOUR
T1 - Structure and extinction of diffusion flames with flame radiation
AU - Chao, B. H.
AU - Law, C. K.
AU - T'ien, J. S.
N1 - Funding Information:
The research performed at Princeton University and Case Western Reserve University were respectively supported by the Division of Basic Energy Sciences of the U.S. Department of Energy under Contract No. DE-FG02-89ERI3988, and by the U.S. Air Force Office of Scientific Research under Grant No. 85-0340.
PY - 1991
Y1 - 1991
N2 - Using droplet combustion as a model problem, and capitalizing on the temperature-sensitive nature of radiative heat transfer, the structure and extinction of diffusion flames with flame radiation is studied via multi-scale activation energy asymptotics. The flame structure analyzed consists of an O(∈) reaction zone embedded within an O(δ) radiation zone which in turn is situated in the O(1) diffusive-convective flow field, where ∈≪δ≪1. The analysis yields the structure equation for the reaction zone, which can be cast in the same form as that of Liñán's adiabatic diffusion flame problem such that his extinction results can be readily used. Present results show that radiative heat loss promotes flame extinction in general, as expected. Furthermore, it can also lead to the phenomenon of dual extinction turning points in which flame extinction due to reactant leakage and thereby kinetic limitation occurs not only for sufficiently small droplets, as is well established, but also for sufficiently large droplets as a result of excessive heat loss from the correspondingly large flame. Consequently there exist diffusive-reactive-radiative systems for which steady combustion is not possible for all droplet sizes. An estimation of the dimensional radiative extinction droplet size is also given for the sample system studied.
AB - Using droplet combustion as a model problem, and capitalizing on the temperature-sensitive nature of radiative heat transfer, the structure and extinction of diffusion flames with flame radiation is studied via multi-scale activation energy asymptotics. The flame structure analyzed consists of an O(∈) reaction zone embedded within an O(δ) radiation zone which in turn is situated in the O(1) diffusive-convective flow field, where ∈≪δ≪1. The analysis yields the structure equation for the reaction zone, which can be cast in the same form as that of Liñán's adiabatic diffusion flame problem such that his extinction results can be readily used. Present results show that radiative heat loss promotes flame extinction in general, as expected. Furthermore, it can also lead to the phenomenon of dual extinction turning points in which flame extinction due to reactant leakage and thereby kinetic limitation occurs not only for sufficiently small droplets, as is well established, but also for sufficiently large droplets as a result of excessive heat loss from the correspondingly large flame. Consequently there exist diffusive-reactive-radiative systems for which steady combustion is not possible for all droplet sizes. An estimation of the dimensional radiative extinction droplet size is also given for the sample system studied.
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U2 - 10.1016/S0082-0784(06)80299-7
DO - 10.1016/S0082-0784(06)80299-7
M3 - Article
AN - SCOPUS:58149207201
SN - 1540-7489
VL - 23
SP - 523
EP - 531
JO - Proceedings of the Combustion Institute
JF - Proceedings of the Combustion Institute
IS - 1
ER -