Flame propagation in grid-induced turbulence☆

Conditional Sampling of Turbulence Intensities and Reynolds Stress in Premixed Turbulent Flames

“…These profiles are typical of those presented in our previous works (Bill et a/., 1982;Cheng and Ng, 1983). In Figure ] As shown by the V profiles, the flame brush thickness increases from 3 mm a t x=60.0 mm to 12 mm at 110.0 mm.…”

Temperature and Velocity Measurements in Premixed Turbulent Flames

“…Also, for unconfined oblique flames they have shown that, due to product gas expansion, there is appreciable deflection of streamlines'approaching the flame and that one overestimates the flame speed if this deflection is not taken into account. This deflection is confirmed by Bill et al 8 for unconfined flames, and for confined duct flames Ho we et al 9 have reported velocity measurements where deflection of cold flow streamlines is evident. Another possible problem with the published data, as noted by Libby et al, 3 is that flame-speed data come from a variety of configurations-normal flames, unconfined oblique flames, and from flames in reaction vessels.…”

“…Durst and Kleine 11 have concluded that "...the observed turbulence in the reaction zone has a natural part of the measured velocity fluctuations as well as a temporal velocity difference resulting from convection of the flame structure across the measuring point which contributes to the overall effective value." Bill et al 8 do not give any significance to increases in turbulence in the reaction zone that they observe and conclude that the lack of correlation iri the reported flame-speed data is due to errors in the measurements. On the other hand, Yule et al 12 have reported measurements on transition from laminar to turbulent flow in a round jet flame.…”

On defining the turbulent burning velocity in premixed V-shaped turbulent flames

“…Previous study [12] has also shown that the maximum density gradient and the maximum density fluctuation also occur close to these positions. Therefore this contour should be identical to the mean flame surface used by Ho et.…”