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.
(462 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).
