Jm. Samaniego et T. Mantel, Fundamental mechanisms in premixed turbulent flame propagation via flame-vortex interactions part I: Experiment, COMB FLAME, 118(4), 1999, pp. 537-556
A combined experimental and numerical study of the interaction of a two-dim
ensional vortex with planar laminar premixed flames has been carried out. I
n such a flaw, the flame is subjected to time-varying strain and curvature
and, hence, the interaction may be viewed as a model of fundamental process
es occurring in premixed turbulent flames. Part I of the paper describes th
e experimental facility and diagnostics employed and presents results from
the experimental investigation of effects of Lewis number, radiative heal l
osses, and unsteadiness on the interaction. A two-dimensional V-shaped lami
nar premixed flame is stabilized on a heated wire in a constant-area square
duct. A two-dimensional vortex pair, generated from a slot in the duct wal
l, eventually interacts with one of the flame fronts. Schlieren and smoke f
low visualization indicate that the flow field remains two-dimensional over
a significant part of the flame-vortex interaction. This feature allows us
e of line-of-sight diagnostics, and, in particular, a CO2* emission imaging
technique for determination of quantitative heat release rates. Several fu
el and oxidizer mixtures are employed in order to vary the Lewis number fro
m 0.8 to 1.6 and to increase the heat loss parameter by a factor of 2.6. Fo
r the conditions investigated, the Lewis and Damkohler numbers are importan
t controlling parameters in the evolution of the heat release rate and radi
ative losses may be neglected. In Part II of the paper, results from direct
numerical simulations of a flame-vortex pair interaction are presented. Th
e simulations were performed using a two-dimensional Navier-Stokes solver i
n which variable density and temperature-dependent transport coefficients a
re considered. The simulations utilize the initial conditions of the experi
ment and were used to investigate the role of multistep chemistry in the fl
ame-vortex interaction. (C) 1999 by The Combustion Institute.