The mathematical modelling and computer simulation of fire development in aircraft

The paper presents a steady-state or transient, three-dimensional mathematical field model describing aircraft cabin fires. The fire is modelled by a simple heat source, and the simulation is intended to represent non-spreading fires. The computer code implementing the model uses a body-fitted coordinate (BFC) formulation to describe accurately the interior of the aircraft, that is neither Cartesian nor polar- cylindrical. The model is first used to predict the experimental results obtained from a series of fire tests performed in a Boeing-737 fuselage (without fittings). Both steady-state and transient results are presented and discussed. Then the effect of openings in the fuselage and cabin compartmentation on the temperature distribution within the empty aircraft cabin is investigated. With the forward and aft bulkhead doors open, allowing for natural convection, the temperatures are kept to tolerable levels. When the forward door is closed while the aft is kept open, temperatures increase throughout the cabin even in the aft section. With both forward and aft doors open, the cabin is partitioned into two communicating sections, the forward section containing the fire. When compared to the non-compartmented case temperatures in the aft section decrease while temperatures in the forward section increase. With the cabin fitted with seats, ceiling panels and overhead stowage bins the effect of the aircraft's air-conditioning system on the temperature distribution within the burning fuselage is examined. The results suggest that a reverse flow situation (i.e. cold air injected through floor vents and hot air sucked out at ceiling vents) greatly reduces the temperature throughout the fuselage. It is concluded that, although insufficiently validated as yet due to the lack of extensive and suitable experimental data, the model is promising.