Predictions of a critical fuel thickness for flame extinction in a quiescent microgravity environment

Bhattacharjee, Subrata; Wakai, Kazunori; Takahashi, Shuhei

doi:10.1016/s0010-2180(02)00501-1

Cited by 26 publications

(11 citation statements)

References 10 publications

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“…The mass pyrolysis rates will decrease more rapidly in larger particles from normal to microgravity conditions for two reasons: (a) the Nusselt time will decrease more (for example by a factor of two as calculations can show) and (b) the loss term in Eq. (3d) will increase more, possibly even leading in some cases to extinction of the burning if the mass flux becomes less than a critical value [17,18,25]. These conclusions are supported by the variation of luminance in Fig.…”

Section: Luminancesupporting

confidence: 53%

“…Although there are some experimental observations reported regarding spherical flame stability under reduced gravity, the combustibles mainly used were gaseous fuel supplied by a porous burner, liquid droplets or PMMA particles [12,14,[17][18][19]. In this paper, different from previous work, solid Methenamine (C 6 H 12 N 4 ), which easily sublimates and decomposes to CH 4 , H 2 and N 2 at about 263°C, is selected as the fuel.…”

Section: Experimental Setup and Proceduresmentioning

confidence: 99%

“…Combustion behavior and flame characteristics under microgravity conditions have attracted extensive research interest [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Under micro-gravity conditions, the buoyancy force owing to gravitational acceleration disappears.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10]), gases (e.g. [11][12][13]) and even solid combustibles [14][15][16][17][18][19][20]. The burning behavior of fuel droplets in microgravity has been investigated extensively for example by Wang [1], Okai [2], Yang [3], Shaw [4,5] and Manzello [6,7] for free fuel droplets or near a wall.…”

Section: Introductionmentioning

confidence: 99%

“…Dreizin [15] revealed the flame evolution characteristics of aluminum particles under microgravity condition. Nakamura [16], Bhattacharjee [17] and Altenkirch [18] investigated the ignition and flame spread and extinction over solid materials under microgravity environment.…”

Section: Introductionmentioning

confidence: 99%

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Experimental study on diffusive solid combustion behavior during transition from normal- to reduced-gravity

Delichatsios

et al. 2012

International Journal of Heat and Mass Transfer

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a b s t r a c tExperiments are carried out in a simplified drop system, which can provide a 2.3 s 10 À2 g reduced gravity period, to investigate the transition of solid material combustion behavior from normal-to reduced-gravity. A CCD camera records the diffusion flames produced by a solid fuel, Methenamine (C 6 H 12 N 4 ), which easily sublimes and decomposes to flammable CH 4 and H 2 . The temperature distribution within the flame is analyzed by a monochromatic line of sight CCD measurement calibrated by a thermocouple measurement. It is revealed that during the transition period from normal-to reduced-gravity, the change of the flame shape, from tall and thin (pear like) to spherical, is faster than that of the luminance which represents the radiation intensity, indicating a relatively shorter adjustment time scale of dynamical gas flow buoyancy than that of the heat transfer when subjected to such a sudden change of gravity condition. It is also found that owing to the change of the flow affecting the oxygen and heat supply, the luminance of the flame as well as the burning rate, which was deduced based on projected area of the solid fuel according to d 2 -law, first decreases followed by an increment near the end of the drop where the gravity level slightly increases. The flame temperature gradually decreases, as the flame suddenly goes into reduced-gravity. Interpretation based on analysis of heat transfer balance and pyrolysis rate as well as the experimental results both indicate that the transitional effect is less pronounced for a smaller fuel particle than for a larger one, where buoyancy is stronger under normal-gravity whereas the flame has a larger standoff distance with increasing importance of the radiation losses from the fuel particle surface under reduced-gravity. The present work is relevant in assessing fire hazards of solid material during space travel as gravity levels change.

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Section: Luminancesupporting

confidence: 53%