Experimental investigation of the flame extinction processes of nonpremixed methane flames inside an air coflow diluted with CO2, N2, or Ar

Radiative emissions measurements from a buoyant, turbulent line flame under oxidizer-dilution quenching conditions

“…Initial extinction results for the present study, in agreement with those of previous works [25][26][27][31][32][33][34][35], show that weakened flames in co-flow lift prior to extinction. As currently understood, this type of extinction is mainly due to weakening of the edge reaction kernel responsible for flame stabilization [25][26][27], a phenomenon more characteristic of partially-premixed flame suppression, than that of the diffusion flames encountered in fire safety applications.…”

“…Similar results have been previously reported, where the observed extinction limit is believed to be dominated by thermal effects rather than strain related effects [28,32,34,35] regimes [26], in the present low-strain, buoyancy-driven flames, these effects are seen to be unimportant in determining the extinction limit.…”

“…As currently understood, this type of extinction is mainly due to weakening of the edge reaction kernel responsible for flame stabilization [25][26][27], a phenomenon more characteristic of partially-premixed flame suppression, than that of the diffusion flames encountered in fire safety applications. It is then questionable whether/how liftoff extinction relates to the suppression of large-scale turbulent flames, where suppression is believed to result from progressive localized extinction throughout the main combustion region [20][21][22][23][24][25][26].…”

“…Others have focused on developing scaling relationships to compare results from different sized configurations [18,19]. It is worth noting that most previous studies have featured small laminar flames, which have proven quite useful for exploring extinction theory [20][21][22][23][24][25][26][27] as well as establishing extinction-limit criteria for flames under quenching action [28][29][30][31][32][33][34][35].…”

Effect of addition of CO2 to the fuel on combustion of gas jets in air

“…In one of the recent works, Min and Baillot [2] obtained extensive experimental information and emphasized the role of the gas-dynamic structure of the flow, but their experimental model (nozzle with thick edges) seems to be not very convenient for interpreting the results from the viewpoint of their influence on macrokinetic characteristics.…”