The behavior of flames spreading over thin solids in microgravity

Ramachandra, Prashant A.; Altenkirch, Robert A.; Bhattacharjee, Subrata; Tang, Lin; Sacksteder, Kurt R.; Wolverton, Mark

doi:10.1016/0010-2180(94)00046-u

Cited by 40 publications

(11 citation statements)

References 5 publications

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“…Hence, the solid fuel cannot receive sufficient heat to pyrolyze fuel vapor continuously and so the solid fuel is retained. Bhattacharjee et al (1993) and Ramachandra et al (1995) experimentally observed this phenomenon in a microgravity environment, and Kumar et al (2003) numerically predicted this phenomenon in a weakly forced flow environment. Figure 9.…”

Section: Resultsmentioning

confidence: 89%

Radiation Effects for Downward Flame Spread Over a Thermally Thin Fuel in a Partial-Gravity Environment

Chen

2004

Combustion Science and Technology

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This study explores the effects of radiation on a downward flame spread over a thermally thin solid fuel in a partial-gravity environment. The radiation effect and gravitational field strength (g) are predicted not to influence the ignition delay time. The flame-spread rate reaches a maximum at g ¼ 0.01. At g > 0.01, the flame stretch effect dominates the behaviors of the flame. Radiation heat transfer and oxygen transport control the flame behaviors for g < 0.01. The predicted quenching limit is g ¼ 5 Â 10 À6 , close to the value obtained experimentally elsewhere. Radiation has two simultaneous effects. One is to reduce the flame strength by carrying heat to the ambient. The other one is combined with upstream conduction to enhance the total forward heat transfer rate and thus preheat virgin fuel upstream. The solid fuel temperature is low and some fuel is left over in low gravity due to radiation loss. Energy analyses indicate that the conduction heat flux from the flame (q c ) dominates its behaviors. However, radiation gradually competes with q c as the gravity is reduced.

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Section: Resultsmentioning

confidence: 89%

Radiation Effects for Downward Flame Spread Over a Thermally Thin Fuel in a Partial-Gravity Environment

Chen

2004

Combustion Science and Technology

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“…Subsequent research on the combustion of thin-sheet materials, conducted in a variety of low-gravity venues, such as drop towers, parabolic-trajectory airplanes, the Shuttle, and Mir, has confirmed these qualitative findings. Moreover, these results show that, for thin solid fuels burning in non-flow (quiescent) microgravity environments, the flammability range (minimum oxygen concentration) is reduced, the fuel mass-loss rate is less, the flame temperature is lower, the rate of heat release is lower, and the soot production is reduced, as compared to the corresponding qualities in normal-gravity combustion [26][27][28]. For thick sheet materials burning in nonflow microgravity environments, the flame-spread rate decreases with time and the flame tends to self-extinguish, although combustion may persist several minutes [29].…”

Section: Fires In Quiescent Air In Microgravitymentioning

confidence: 93%

“…A series of Shuttle tests, the Solid Surface Combustion Experiment (SSCE), provided quantitative data on the effects of atmospheric oxygen concentration and total pressure on thin-paper flame spread in quiescent microgravity [27]. A summary of flame-spread rate determinations is shown in Fig.…”

Section: Oxygen-assisted Fires In Microgravitymentioning

confidence: 99%

Fire Safety in the Low-Gravity Spacecraft Environment

Friedman

1999

SAE Technical Paper Series

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Research in microgravity (low-gravity) combustion promises innovations and improvements in fire prevention and response for human-crew spacecraft. Findings indicate that material flammability and fire spread in microgravity are significantly affected by atmospheric flow rate, oxygen concentration, and diluent composition. This information can lead to modifications and correlations to standard material-assessment tests for prediction of fire resistance in space. Research on smoke-particle changes in microgravity promises future improvements and increased sensitivity of smoke detectors in spacecraft. Research on fire suppression by extinguishing agents and venting can yield new information on effective control of the rare, but serious fire events in spacecraft.

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“…For thermally-thin fuel, a steady flame spread can be achieved in a quiescent environment when the oxygen percentage is sufficiently high (Bhattacharjee and Altenkirch 1990;Ramachandra et al 1995;Kumar et al 2003), which is considered as a special case of opposed flame spread. However, the limiting flow velocity for steady concurrent flame spread to occur over a thin fuel is finite and does not go to zero.…”

Section: Introductionmentioning

confidence: 99%

Flame Spread and Extinction Over a Thick Solid Fuel in Low-Velocity Opposed and Concurrent Flows

Zhu

Wang

2015

Microgravity Sci. Technol.

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Flame spread and extinction phenomena over a thick PMMA in purely opposed and concurrent flows are investigated by conducting systematical experiments in a narrow channel apparatus. The present tests focus on lowvelocity flow regime and hence complement experimental data previously reported for high and moderate velocity regimes. In the flow velocity range tested, the opposed flame is found to spread much faster than the concurrent flame at a given flow velocity. The measured spread rates for opposed and concurrent flames can be correlated by corresponding theoretical models of flame spread, indicating that existing models capture the main mechanisms controlling the flame spread. In low-velocity gas flows, however, the experimental results are observed to deviate from theoretical predictions. This may be attributed to the neglect of radiative heat loss in the theoretical models, whereas radiation becomes important for low-intensity flame spread. Flammability limits using oxygen concentration and flow velocity as coordinates are presented for both opposed and concurrent flame spread configurations. It is found that concurrent spread has a wider flammable range than opposed case. Beyond the flammability boundary of opposed spread, there is an additional flammable area for concurrent spread, where the spreading flame is sustainable in concurrent mode

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The behavior of flames spreading over thin solids in microgravity

Cited by 40 publications

References 5 publications

Radiation Effects for Downward Flame Spread Over a Thermally Thin Fuel in a Partial-Gravity Environment

Radiation Effects for Downward Flame Spread Over a Thermally Thin Fuel in a Partial-Gravity Environment

Fire Safety in the Low-Gravity Spacecraft Environment

Flame Spread and Extinction Over a Thick Solid Fuel in Low-Velocity Opposed and Concurrent Flows

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