Fire Suppression and Re-ignition Prevention in a Full-Scale Engine Nacelle Simulator.
Fire Suppression and Re-ignition Prevention in a
Full-Scale Engine Nacelle Simulator.
Hamins, A.; Cleary, T. G.; Yang, J. C.
Fire Safety Science. Proceedings. Seventh (7th)
International Symposium. International Association for
Fire Safety Science (IAFSS). June 16-21, 2003,
Worcester, MA, Intl. Assoc. for Fire Safety Science,
Boston, MA, Evans, D. D., Editor, 703-714 p., 2003.
fire research; nacelle engines; fire suppression;
ignition; aircraft safety; halon 1301; effectiveness;
premixed flames; concentration measurement; flame
stability; flammability limits
An analysis is presented on the full-scale fire
suppression experiments conducted on the F-22 engine
nacelle simulator at Wright Patterson Air Force Base.
Experiments investigated the relative effectiveness of
halogenated agents and solid propellant gas generators
(SPGG) in suppressing a series of spray fires with and
without a fuel re-ignition source. Several agents were
tested including CF3Br (halon 1301), C2HF5 (HFC-125),
and two basic types of SPGG, including one that produced
inert gases in conjunction with a fine solid particulate
composed of K2CO3 and one that produced inert gases
only. The measured agent effectiveness was compared to
the predicted effectiveness based on results from cup
burner suppression experiments. Estimates of the
suppression effectiveness of the SPGG were based on the
effectiveness of the components of its effluent. The
mass fraction of SPGG effluent required to extinguish
heptane cup burner flames was estimated as 0.15 and 0.29
as compared to previously measured values of 0.14 and
0.28 for CF3Br and C2HF5, respectively. The predicted
suppression requirements (relative to CF3Br) agreed with
the full-scale measurements within 35% for the
halogenated compounds, whereas the SPGG performed as
much as a factor of 3.3 better than predicted. This
difference suggests that a large fraction of the SPGG
performance may have been related to its fast
deployment, which enhances flame straining and thereby
reduces agent mass suppression requirements. The SPGG
effluent that contained a significant percentage of
K2CO3 particulate was particularly effective for
re-ignition protection, a scenario that dominates agent
mass requirements for the compressed halogenated
liquids. In this case, the SPGG required 27 times less
mass than CF3Br.