Liquid Agent Transport Around Solid Obstacles.
Liquid Agent Transport Around Solid Obstacles.
(654 K)
Presser, C.; Widmann, J. F.; Papadopoulos, G.
NIST SP 984; June 2002.
Halon Options Technical Working Conference, 12th.
Proceedings. HOTWC 2002. April 30-May 2, 2002,
Albuquerque, NM, Gann, R. G.; Reneke, P. A.,
Editor(s)(s), 1-12 pp, 2002.
Available from:
Both the presentations and the papers are available on
the HOTWC web site:
http://www.bfrl.nist.gov/866/HOTWC/HOTWC2002/index.htm
Keywords:
halons; halon alternatives; computational fluid
dynamics; fire suppression; turbulent flow; validation
Abstract:
The focus of this effort is to investigate the dispersal
of liquid fire suppression agents around solid
obstacles, and obtain a better understanding of the
physical processes of droplet transport in cluttered
spaces. An experimental investigation is presented to
examine the flow field dynamics of highly turbulent flow
over obstacles, and spray transport in such flow fields.
The obstacles of interest were a cylinder and
body-centered cube (BCC) arrangement of spheres.
Transport of both water droplets and seed particles was
characterized upstream and downstream of these obstacles
using particle image velocimetry (PIV). Data were
recorded for the cylinder at ambient temperature and
after being heated to 423 K to estimate the effects of
the hot cylinder surface on droplet transport. The
results indicate that smaller droplets are entrained
into the recirculation region behind the cylinder while
the larger droplets impact the cylinder surface,
accumulate, and drip off, or disperse radially away from
the surface regardless of their interaction with the
cylinder. The flow over the heated cylinder indicates
the formation of layer of vaporizing liquid on the
downstream side of the cylinder in the shear region
between the recirculation zone and free stream. In
addition, surface cooling that resulted from spray
impingement was around 50D% of the preset cylinder
temperature. For the BCC (with a blockage ratio of about
64D%), there is both transport of droplets and seed
particles around and through the BCC, as well as
significantly more liquid accumulation and dripping than
for the cylinder.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899