Fs. Costa, EFFECTS OF DIFFERENTIAL DIFFUSION ON UNSTEADY DIFFUSION FLAMES, International communications in heat and mass transfer, 25(2), 1998, pp. 237-244
The effects of differential diffusion on unsteady diffusion flames are
considered far one-dimensional geometries. A Stefan problem is obtain
ed for a single planar flame separating two semi-infinite regions cont
aining fuel and oxidizer. Non-unity diffusivity ratio and the stoichio
metry affect strongly the flame evolution and determine the conditions
to obtain a stationary flame. A fuel strip surrounded by an oxidizer
is considered and its burning can represent the burning of a gas pocke
t or supercritical droplet. It is demonstrated for a fuel strip that i
ncreasing O/F diffusivity ratios decrease the maximum flame expansion
and decrease the burning times, while increasing initial equivalence r
atios will increase the maximum flame expansion and will increase the
burning times. (C) 1998 Elsevier Science Ltd.