Combined effects of curvature, radiation, and stretch on the extinction of premixed tubular flames

Extinction of premixed methane/air flames in microgravity by diluents: Effects of radiation and Lewis number

“…The combined effects of stretch and radiation on premixed flames have been studied by several researchers [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. Farmer and Ronney [17] numerically examined the dynamics properties of near-limit CH 4 /air flames in planar and spherical geometries considering radiative heat loss from CO 2 and H 2 O.…”

“…Wang and Niioka [31] numerically investigated radiation reabsorption effects in CH 4 -air counterflow premixed flames and found that the reabsorption of emitting radiation leads to substantially wider flame thickness and higher flame temperature than those calculated by using the optically-thin model. Ju and his co-workers [23][24][25][26][27][28][29][30]34,35] conducted extensive studies on the combined effects of radiation and stretch on flammability limits for various Lewis number mixtures. In particular, their recent work [34] show that the flame geometry has a significant impact on radiation absorption and that the 1-D planar radiation model was not valid for the computation of the flame speed of a spherical flame.…”

Theoretical analysis on the transient ignition of a premixed expanding flame in a quiescent mixture

“…Though heat is still supplied from the kernel centre towards the flame front for , it gradually reduces as the flame propagates outwardly. When the heat generation from chemical reaction and heat conduction from the kernel centre is overbalanced by the heat loss in the preheat zone, the flame structure cannot be maintained and extinction occurs (Chen & Ju 2008). For the same heating power of , a slightly longer heating time, e.g.…”

“…For simplicity, we consider the development of the ignition kernel in a quiescent mixture under microgravity conditions. Providing that the stoichiometric ratio of the mixture is far away from the flammability limit, the impacts of radiation heat loss upon the propagation of the flame kernel appears to be quantitative instead of qualitative (Chen & Ju 2008; Chen 2017). The volumetric radiative heat loss is proportional to the cube of the flame kernel radius which is comparably small, i.e.…”

Analysis of Completely Prevaporized Spray Flames with Water/Octane Core/Shell Structured Droplets

“…Owing to the successful introduction of large activation energy asymptotics in combustion, great progress has been made in understanding the physics of the flame [1][2][3][4][5][6]. As a result, numerous investigations have been devoted to asymptotic theories of steady deflagrations with heat losses [7][8][9][10][11][12][13][14][15], stretch [9,11,[15][16][17], and preferential diffusion (nonunity Lewis number) [12,13,18].…”