A study of propagation of spherically expanding and counterflow laminar flames using direct measurements and numerical simulations

On the accuracy of laminar flame speeds measured from outwardly propagating spherical flames: Methane/air at normal temperature and pressure

“…These sources include mixture preparation [5,9,27,28], ignition [29][30][31][32], buoyancy [33,34], instability [35][36][37], confinement [38][39][40][41], radiation [9,10,[41][42][43][44], nonlinear stretch behavior [22,[45][46][47][48][49], and extrapolation [50,51]. The references cited above provide information or details about the effects of each source on S 0 u measured using the OPF method.…”

“…Since sphere flame propagation at small and large radii is affected differently by those factors discussed above, the choice of flame radius range used for extrapolation, [R fL , R fU ], is another influential component which affects S 0 u measured using the OPF method [50,51].…”

“…Therefore, extrapolation might lead to great discrepancy in S 0 u measurement using the OPF method [10,[48][49][50][51]. Recently, Jayachandran et al [10,51] and Varea et al [49] have suggested to directly compare the measured quantities instead of extrapolated ones with 1-D simulation results predicted by kinetics so that the uncertainty associated with extrapolation can be eliminated.…”

“…Recently, Jayachandran et al [10,51] and Varea et al [49] have suggested to directly compare the measured quantities instead of extrapolated ones with 1-D simulation results predicted by kinetics so that the uncertainty associated with extrapolation can be eliminated. Figures 13 and 14 shows the comparison among experiential data reported in the literature and present simulation results for 1-D propagating spherical CH 4 /air flames at NTP with / = 0.8, 1.0,and 1.2.…”

“…Specifically, a variety of experimental data sets for CH 4 /air reported in the literature [13][14][15][16][17][18][19][20][21][22][23][24][25][26] is collected to show the differences in S 0 u measurement using the OPF method. Moreover, effects of mixture preparation [5,9,27,28], ignition [29][30][31][32], buoyancy [33,34], instability [35][36][37], confinement [38][39][40][41], radiation [9,10,[41][42][43][44], nonlinear stretch behavior [22,[45][46][47][48][49], and extrapolation [50,51] on the discrepancies in S 0 u measurement are examined based on 1-D simulation of propagating planar and spherical flames. It should be noted that Egolfopoulos et al [5] have recently reviewed possible sources of uncertainty in S 0 u measurement using the OPF method.…”