An experimental study of microgravity combustion of a droplet near a wall

Okai, Keiichi; Tsue, Mitsuhiro; Kono, Michikata; Sato, Junichi; Dietrich, Daniel L.; Williams, Forman A.

doi:10.1016/s0010-2180(02)00573-4

Cited by 6 publications

(5 citation statements)

References 8 publications

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“…(3d) includes that conducted into the particle and especially the re-radiation losses from the surface, which are very important for large solid particles (>5 mm here) compared to the small droplets (less than 1 mm) usually investigated in the literature [1][2][3][4][5][6][7][8][9][10][11]. Based on Eqs.…”

Section: Luminancementioning

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].…”

Section: Introductionunclassified

“…[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. Yozgatligil [8] has revealed the sooting behavior of ethanol droplet combustion under micro-gravity conditions through the 2.2-s drop tower at NASA Glenn Research Center.…”

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: Luminancementioning

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].…”

Section: Introductionunclassified

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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“…Another important parameter in the droplet combustion is the role of cooled wall. Also Okai et al [2] performed reduced-gravity experiments with heptane droplets burning near cool walls. Dombrovsky and Sazhin [3] formu-lated the boundary-value problem for calculation of differential absorption of thermal radiation on a spherical droplet.…”

Section: Introductionmentioning

confidence: 99%

The effect of fuel pyrolysis on the coal particle combustion: An analytical investigation

et al. 2016

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The aim of this work is to analytically investigate the symmetrical combustion of an isolated coal particle with the fuel pyrolysis effect. The modelling concept of coal particles is similar to that of the liquid droplet combustion but in the case of coal devolatilization, the particles do not shrink like droplet does due to evaporation of liquid fuel. The rate of devolatilization of volatiles can be calculated using the equation that is similar to Arrhenius equation. This model is based on an assumption of combined quasi-steady and transient behaviour of the process and especially focuses on predicting the variations of temperature profile, radius of pyrolysis and transfer number. It is revealed that the entrance of pyrolysis effect into the governing equations leads to the reduction in the film radius and consequently a reduction in the stand-off ratio and transfer number.

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“…Chemical reactions, non-unity Lewis number, transient liquid phase heating [3], fuel vapor accumulation in gas phase [4], variable transport properties [5], water condensation into fuel droplet [6][7][8], thermal radiation [9,10] and soot [11,12] influence characteristics of the droplet combustion. It has been reported that the burning rate constant is dependent on the initial droplet diameter, especially for sooting fuels [8,13,14].…”

Section: Introductionmentioning

confidence: 99%

Combustion behaviors of isolated n-decane and ethanol droplets in carbon dioxide-rich ambience under microgravity

Nakaya¹,

Segawa²,

Kadota³

et al. 2011

Proceedings of the Combustion Institute

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An experimental study of microgravity combustion of a droplet near a wall

Cited by 6 publications

References 8 publications

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

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

The effect of fuel pyrolysis on the coal particle combustion: An analytical investigation

Combustion behaviors of isolated n-decane and ethanol droplets in carbon dioxide-rich ambience under microgravity

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