FirefightingNew Fire-Simulating Tool Could Improve In-Flight Fire Safety

Some of the most dangerous fires are the ones you don’t see coming. That goes not only for fires in buildings but for those kilometers off the ground, aboard commercial airliners. Many aircraft have systems to detect fires early on, but fires that spark in their attics, or overhead compartments — spaces with curved ceilings, filled with air ducts, electrical wiring and structural elements — could potentially sneak past them. 

“Attic fires are less likely to occur than elsewhere in a plane, but they are hard to detect,” said Haiqing Guo, a contract fire research scientist at the Federal Aviation Administration (FAA). “By the time you see it, it’s too late.” 

Fire detector placement in overhead compartments is particularly challenging for fire protection engineers as it is unclear how to predict where smoke will travel amid the irregularly shaped clutter. A fire-simulating computer model developed at the National Institute of Standards and Technology (NIST) could now offer some much-needed guidance thanks to recent updates. In a new study, a team of NIST and FAA researchers tested the tool against a real-world scenario, where fires burned inside a grounded airliner, and found that the software closely replicated measured temperatures and correctly identified hot spots in the attic. 

NIST’s Fire Dynamics Simulator, or FDS, simulates the flow of heat and smoke produced by fires. Since its launch in 2000, the software has been used by engineers across the globe to design fire protection systems for buildings and for forensic reconstructions of real-life fires. In both cases, engineers use the software to learn how a fire would or did burn without having to perform full-scale tests first, which are costly and sometimes impractical to run. 

FDS can reliably model the behavior of a fire in the presence of flat surfaces and block-like objects. This capability is good enough for the lion’s share of scenarios, as most rooms are rectangular in shape.  But curved surfaces, such as uneven terrain outdoors or the ceilings of trains and planes, have sometimes thrown the software for a loop. 

To manage this limitation, engineers using past iterations of FDS would approximate curved surfaces with small boxes, but a new version can do better. A recent update allows FDS to understand smoother surfaces made of triangles, bringing its simulations closer to reality in certain cases.