L. Muniz et Mg. Mungal, Effects of heat release and buoyancy on flow structure and entrainment in turbulent nonpremixed flames, COMB FLAME, 126(1-2), 2001, pp. 1402-1420
Particle image velocimetry was used to examine the velocity fields in the n
ear- and far-field of the axisymmetric jet in co-flow under nonreacting and
reacting conditions. The jets studied include nonreacting jets at Re-o = 1
0,000 and 2,000 and flames at Re-o = 10,000 and 37,500. Qualitatively, heat
release was seen to impact the instantaneous flow structure over the first
third of the flame length by restricting the large-scale movement of the j
et. The instantaneous flow structure over the remainder of the flame length
was less affected by heat release, a possible consequence of the lower den
sity gradients. Heat release was seen to impact the mean characteristics of
the flow by reducing the local Reynolds number by a factor of 10 over the
length of the flame and reducing the global entrainment rate by similar to
50%. In addition, heat release acted to narrow the jet width up to 20%. red
uce the turbulence intensities up to 40%, and increase the centerline-veloc
ities by factors of 2 to 3. The effects of buoyancy resulting from heat rel
ease were also examined and tended to counteract the effects of heat re;eas
e by promoting entrainment and increasing turbulence intensity. (C) 2001 by
The Combustion Institute.