Premixed flame propagation in vertical tubesстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 19 июля 2016 г.
Аннотация:Analytical treatment of the premixed flame propagation in vertical tubes with smooth
walls is given. Using the on-shell flame description, equations for a quasi-steady
flame with a small but finite front thickness are obtained and solved numerically.
It is found that near the limits of inflammability, solutions describing upward flame
propagation come in pairs having close propagation speeds and that the effect of
gravity is to reverse the burnt gas velocity profile generated by the flame. On the
basis of these results, a theory of partial flame propagation driven by a strong
gravitational field is developed. A complete explanation is given of the intricate
observed behavior of limit flames, including dependence of the inflammability range
on the size of the combustion domain, the large distances of partial flame propagation,
and the progression of flame extinction. The role of the finite front-thickness effects
is discussed in detail. Also, various mechanisms governing flame acceleration in
smooth tubes are identified. Acceleration of methane-air flames in open tubes is
shown to be a combined effect of the hydrostatic pressure difference produced by
the ambient cold air and the difference of dynamic gas pressure at the tube ends.
On the other hand, a strong spontaneous acceleration of the fast methane-oxygen
flames at the initial stage of their evolution in open-closed tubes is conditioned by
metastability of the quasi-steady propagation regimes. An extensive comparison of
the obtained results with the experimental data is made.