Dispersion of Fire Suppression Agents Discharged From High Pressure Vessels: Establishing Initial/Boundary Conditions for the Flow Outside the Vessel.
Dispersion of Fire Suppression Agents Discharged From
High Pressure Vessels: Establishing Initial/Boundary
Conditions for the Flow Outside the Vessel.
(1801 K)
Cooper, L. Y.
NISTIR 5219; Paper XIII-2; 37 p. September 1993.
Institute for Liquid Atomization and Spray Systems
(ILASS-Europe) and CORIA. Liquid Atomization and Spray
Systems, 6th International Conference Proceedings.
ICLASS 94. July 18-22, 1994, Rouen, France, Begell
House, Inc., NY, Yule, A. J.; Dumouchel, C.,
Editor(s)(s), 1031-1038 pp, 1993.
Sponsor:
Air Force, Wright Patterson AFB, OH
Available from:
National Technical Information Service
Order number: PB94-103660
Keywords:
fire extinguishing agents; aircraft safety; discharge
pressure; fire extinguishment; fire safety; halons; fire
suppression; halon alternatives; pressure vessels
Abstract:
This work reports on part of an effort to study the
dispersion and extinguishment effectiveness of Halon and
Halon-alternative fire extinguishment agents discharged
from N2-pressurized vessels. In the systems under
consideration, as the agent exits from the vessel,
thermodynamic and fluid-dynamic instabilities lead to
flashing and break-up of the agent into a two-phase
droplet/gaseous jet mixture. This occurs in a
transition region relatively close to the vessel exit
orifice/nozzle. Downstream of this region the two-phase
agent jet then mixes with the ambient air environment
and is dispersed in the protected space. A mathematical
model has been developed previously to simulate the
time-dependent discharge of the agent from the pressure
vessel. Using the output of this model and
thermodynamic and fluid-dynamic considerations of the
phenomena in the transition section, the present work
develops a method for determining a set of
initial/boundary conditions at an initial section of the
jet, downstream of the transition region. These
initial/boundary conditions are in a form that can be
used to formulate and solve the problem of the
development and dispersal of the ensuring mixed
air/two-phase-agent jet. Example applications of the
developed methodology are presented. These are for
agent discharge from a half-liter cylindrical discharge
vessel with a circular discharge nozzle/orifice of
diameter 0.019m. Simulations involve discharge of the
vessel when it is half-filled with either Freon 22 or
Halon 1301 and then pressurized with N2 to 41.37x105Pa
(600 psi).
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899