The Defense Advanced Research Projects Agency (DARPA) published the following video demonstrating how a fire could be extinguished using sound:
Wired’s Danger Room has more:
The team arranged two speakers either side of a liquid fuel flame to demonstrate how fire can be controlled by amping up an acoustic field. The sound increases air velocity, which then thins the area of the flame where combustion occurs, known as the flame boundary. Once the boundary area is thinned, the flame is easier to extinguish. At the same time, the acoustics are disturbing the pool of fuel and creating higher fuel vaporisation — this widens the flame, thinning it out so it is less concentrated and cool enough to extinguish.
Even better, the sound does not even need to be offensively loud to achieve any of this.
“We have shown that the physics of combustion still has surprises in store for us,” commented Darpa manager Matthew Goodman in a statement. “Perhaps these results will spur new ideas and applications in combustion research.”