Diffusion Flame Extinguishment in Microgravity
- Paper number
IAC-05-A2.7.05
- Author
Dr. Fumiaki Takahashi, National Center for Microgravity Research, United States
- Coauthor
Dr. Gregory Linteris, United States
- Coauthor
Dr. Viswanath Katta, United States
- Year
2005
- Abstract
To enable NASA’s human exploration of the moon and Mars, fire safety for spacecraft and planet surface bases is essential for mission success. The longer-duration missions for space exploration, however, increase the likelihood of accidental fire events aboard spacecraft or in surface habitats. To develop effective fire protection systems, the behavior of fires in various environments to be encountered in space exploration must be properly understood. Fire behavior and suppression processes in space exploration missions are strongly influenced by the low-gravity conditions, both in flight and on the planetary surfaces. The purposes of the present study are to understand the physical and chemical processes of flame suppression phenomena and to provide rigorous testing of numerical models in various oxidizing environments relevant to the space exploration missions, so that appropriate and effective prevention and mitigation strategies can be designed.
The effects of oxidizer stream velocity and oxygen concentration, as well as gravity and pressure, on unsteady extinguishment phenomena of laminar co-flow diffusion flames of methane, formed in a cup-burner apparatus, have been studied experimentally and computationally. A gaseous fire-extinguishing agent (CO2, N2, He, Ar, or CF3H) was introduced gradually into a coflowing oxidizer stream until blowoff-type extinguishment occurred. A first attempt was made to measure the cup-burner minimum extinguishing concentration (MEC) (i.e., a volume fraction) in microgravity aboard the NASA Reduced Gravity Aircraft. Numerical simulations with full chemistry and radiative heat-loss models were performed to reveal the flame structure during the unsteady blowoff-type extinguishing processes and to predict the extinguishment limits. Despite the complexity of chemistry and flame-flow interactions in the blowoff processes, the numerical predictions of MECs were generally in good agreement with the measurements. More importantly, the MECs in microgravity were, in general, higher (more difficult to extinguish) than in normal earth gravity.
bf Acknowledgment: This work was supported by the Office of Biological and Physical Research, National Aeronautics and Space Administration, Washington, DC.
- Abstract document
- Manuscript document
IAC-05-A2.7.05.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.