Suppression Effectiveness Studies of Halon-Alternative Agents in a Detonation/Deflagration Tube.
Suppression Effectiveness Studies of Halon-Alternative
Agents in a Detonation/Deflagration Tube.
Gmurczyk, G. W.; Grosshandler, W. L.
Halon Options Technical Working Conference.
Proceedings. HOTWC 1994. May 3-5, 1994, Albuquerque, NM,
193-204 pp, 1994.
halons; fire suppression; halon 1301; in-flight fires;
fire protection; detonation; deflagration;
effectiveness; predictive models; fire extinguishing
agents; halon alternatives; dynamic characteristics
Experimental studies of the effect of the presence of
halon-alternative agents on the suppression of premixed
high-speed turbulent flames and quasi-detonations have
been carried out in a 7.5 m long, 50 mm diameter tube.
Lean and stoichiometric C2H4/air mixtures in the absence
of any halocarbon, initially at 100 kPa and 295 K,
constitute the reference states. A primary objective of
the work has been to determine the relative suppression
efficiencies of different agents under highly dynamic
situations, without the undue influence of either the
ignition event of the mixing of the agent into the flame
front. This was accomplished by generating a highly
turbulent flame/quasi-detonation in the driver section,
which contained no suppressant, followed by measurements
of the velocity and pressure ratio as the wave front
entered the test section of the tube, which contained
suppressant premixed with the same fuel/air combination.
A turbulence generator in the form of a spiral
obstruction was used in the tube to broaden the gas
dynamic conditions attainable by the flame. Flame and
shock wave velocities up to 1300 m/s, pressure ratios
across the shock fronts over 26:1, and shock wave/flame
spacings of the order of 10 cm were measured with
piezo-electric pressure transducers and fast
photodiodes. The experimental facility was successfully
employed to clearly discriminate among the dynamic
characteristics of the five compounds, revealing
behavior distinct from what was observed in companion
studies using atmospheric non-premixed flames. The
suppression process is strongly influenced by the
concentration of an agent, the structure and composition
of an agent molecule, and the composition of the
combustible mixture itself. The results were compared
with the situation when an agent is fully premixed with
the combustible mixture in the tube.