Much to pundits’ disappointment, you can’t solve most environmental ills just by yelling at them. But, as the Defense Advanced Research Projects Agency (DARPA) has discovered, it does work for one thing: fires. DARPA’s “Instant Fire Suppression” program uses sound to put out flames — and it doesn’t even need to be that loud.
The sound makes flames easier to extinguish by increasing air velocity, which thins the flame boundary — the part of the fire where combustion occurs. Disturbance from the sound waves also makes liquid fuel evaporate faster, so the fire is less self-sustaining.
This was mainly developed for putting out fires in enclosed areas like airplane cockpits, where a flame can be incredibly dangerous. (So can an incredibly loud noise, kinda — but the good news is that acoustic fire suppression doesn’t have to be at an intolerable level.) But maybe someday they can set up giant yelling machines for fires like the one in Colorado. Until then, we’ll just have to yell from here.
Video: Darpa’s ‘Wall-of-Sound’ Fire Extinguisher, Wired.
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