Experimental and Numerical Studies on Two-Dimensional Gravity Currents in a Horizontal Channel.
Experimental and Numerical Studies on Two-Dimensional
Gravity Currents in a Horizontal Channel.
(13585 K)
Chan, W. R.; Zukoski, E. E.; Kubota, T.
NIST GCR 93-630; 261 p. July 1993.
Sponsor:
National Institute of Standards and Technology,
Gaithersburg, MD
Available from:
National Technical Information Service
Order number: PB94-165941
Keywords:
compartment fires; fire models; fire research; gravity
current; inclined tests; room fires; smoke
Abstract:
The objective of this investigation is to examine the
behavior of two-dimensional gravity currents, especially
as applied to the spreading of smoke, generated from a
room fire, along a long corridor. Both experimental and
numerical techniques were used to provide a model that
can adequately explain and predict the behavior of a
gravity current under certain boundary conditions. A
series of experiments was carried out to study the
effects of Reynolds number on gravity currents in a
horizontal water channel. Measurements of the time
varying front position, velocity profile of the
following current, and the depth of a gravity current
were made using either dyed liquids or hydrogen bubble
technique. Quantitative results were shown to agree
with previously published results. A model was put
forth to bridge the gap between the existing models for
an inertia-buoyancy dominated gravity current and a
viscous-buoyancy dominated one. Comparison between the
experimental results and numerical results obtained from
the model proved that the model can adequately explain
the behavior of the phenomenon. A second series of
experiments was conducted to investigate the behavior of
gravity currents in an inclined channel. The
quantitative results obtained were less scattered than
those obtained in previous research. The gravity
current was found to be unsteady in a horizontal
channel, while a channel with an angle of inclination of
one degree was found to produce a steady flow behind the
front of the gravity current. The change of the gravity
currents from an unsteady to a steady nature due to the
change in the inclination of the channel was found to be
gradual and much less abrupt than assumed in previous
studies.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899