Propagation and quenching of premixed flames in narrow channels |
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Authors: | Z B Song X W Ding J L Yu Y Z Chen |
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Affiliation: | (1) China Academy of Safety Science and Technology, Beijing, China;(2) Institute of Chemical Engineering, Dalian University of Technology, Dalian, Liaoning, China |
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Abstract: | The shape and propagation of unsteady premixed flames in narrow channels with adiabatic and isothermal walls are numerically
investigated in the present study. The flame chemistry is modelled by an one-step overall reaction, which simulates the reaction
of a stoichiometric acetylene-air mixture. The numerical results show that both ignition methods and thermal boundary conditions
affect flame formation and its shape. The flame keeps a single tulip shape in the whole process of propagating through the
channel if plane ignition is used and a single mushroom shape if spark ignition is used. For isothermal cold walls, the flame
cannot keep a single tulip shape or mushroom shape all the time. Under plane ignition, a transition from a tulip-shaped flame
to a mushroom-shaped flame occurs as flames propagate from one end of channel to the other. Under spark ignition, the process
is just the contrary. It is also shown that the heat loss at the cold walls has a dual effect on the formation of a tulip-shaped
flame. Flame propagation and quenching in narrow channels of different heights are analyzed systematically, and a criterion
is proposed to judge the flame states of partial extinction and total extinction. It is called the criterion of flame propagation
and quenching in narrow channels.
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Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 3, pp. 27–36, May–June, 2006. |
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Keywords: | narrow channel tulip-shaped flame mushroom-shaped flame heat loss quenching |
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