- Author
-
Lyon, R. E.
|
Blake, D.
- Title
- Heat Release Rate of Objects Burning in Cargo Compartments.
- Coporate
- Federal Aviation Administration, Atlantic City International Airport, NJ
- Report
-
DOT/FAA/AR-TN05/9
April 2005
11 p.
- Keywords
-
cargo compartments
|
heat release rate
|
combustion
|
smoke
|
smoke detectors
|
fire detectors
|
cargo space
|
commercial aircraft
|
photoelectric detectors
|
computational fluid dynamics
- Identifiers
- comparison of calculated and best-fit parameters for propane burner calibration of cargo compartment model
- Abstract
- To support the development of more reliable fire detectors and facilitate their certification for commercial aircraft, the Federal Aviation Administration (FAA) is conducting research to generate a complete and reproducible fire signature typical of a luggage article burning in a cargo compartment. Aircraft manufacturers primarily use photoelectric smoke detectors, and to a lesser extent ionization detectors, to comply with FAA regulations for fire detection in cargo compartments of commercial aircraft. The photoelectric detectors rely on smoke particles entering a chamber where they either reflect or attenuate a light beam to produce an alarm. While effective at detecting smoke, these detectors also alarm when airborne particles or moisture are detected. The current ratio of false alarms to real fires in commercial aircraft cargo compartments is on the order of hundreds-to-one. The low reliability (< 1%) of current fire detectors is costly to airlines, so detectors are being developed that alarm only after multiple fire products are sensed, e.g., optical extinction, temperature, carbon monoxide, hydrocarbons, etc. The location of the fire source and the movement of fire products within the cargo compartment is important for optimum placement of fire detectors. A computational fluid dynamics (CFD) model is being developed in combination with an experimental program to address this issue. The CFD model requires a well-characterized fire product source. A composite sample was developed for this purpose, which is comprised of several different plastics in the approximate ratio found in passenger luggage. The history of heat release rate, smoke density, and combustion gas composition of the plastic composite in flaming and nonflaming modes was measured in a bench-scale fire (cone) calorimeter to obtain its fire signature. Full-scale testing of luggage articles and the plastic composite in a ventilated Boeing 707 cargo compartment revealed that the fire signature deduced from the exhaust gases was smeared due to volumetric mixing in the cargo compartment. Consequently, a simple mixing model was evaluated to determine whether time-deconvolution of the exhaust gas history could be used to provide the fire signature of a burning object in the (relatively) large cargo compartment of a commercial passenger jet. The model was evaluated by comparing known heat release rate histories in the cargo compartment from a premixed propane burner to those calculated from the mixing model using the oxygen consumption history of the exhaust gases.