Ignition, Transition, Flame Spread in Multidimensional Configurations in Microgravity.
Ignition, Transition, Flame Spread in Multidimensional
Configurations in Microgravity.
(555 K)
Kashiwagi, T.; Mell, W. E.; Baum, H. R.; Olson, S. L.
NASA/CP-1999-208917;
Microgravity Combustion Workshop, Fifth (5th)
International. Proceedings. Sponsored by NASA Office
of Life and Microgravity Sciences and Applications and
the Microgravity Combustion Science Discipline Working
Group hosted by NASA Glenn Research Center and the
National Center for Microgravity Research on Fluids and
Combustion. NASA/CP-1999-208917. May 18-20, 1999,
Cleveland, OH, 333-336 pp, 1999.
Keywords:
microgravity; flame spread; fire safety; ignition
Abstract:
In the inhabited quarters of orbiting spacecraft, fire
is a greatly feared hazard. Thus, the fire safety
strategy in a spacecraft is (1) to keep any fire as
small as possible, (2) to detect any fire as early as
possible, and (3) to extinguish any fire as quickly as
possible. This suggests that a material which undergoes
a momentary ignition might be tolerable but a material
which permits a transition from a localized ignition to
flame spread would significantly increase the fire
hazard in a spacecraft. If the transition does not take
place, fire growth does not occur. Therefore, it is
critical to understand what process controls the
transition. Many previous works have studied ignition
and flame spread separately or were limited to a
two-dimensional configuration. In this study;
time-dependent phenomena of the transition over a
thermally thin sample is studied experimentally and
theoretically in two- and three-dimensional (2D, 3D)
configurations. Furthermore, localized ignition can be
initiated at the center portion of thermally thin paper
sample instead of at one end of the sample. Thus, the
transition to flame spread could occur either toward
upstream or downstream or both directions simultaneously
with an external flow. In this presentation, the
difference in the transition between the 3D and 2D
configurations is explained with the numerically
calculated data. For sufficiently narrow samples edge
effects exist. Some results on this issue are presented.
New analysis of the surface smoldering experiments
conducted in the space shuttle STS-75 flight is also
described.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899