Firefighters may soon have a new weapon in their battle against flames: physics.
Boffins at US military research unit Defense Advanced Research Projects Agency (Darpa) were looking for an alternative approach to dousing a fire in chemicals, which can often result in damage to precious materials.
So instead, the researchers came up with a technique for extinguishing fire with sounds (see video below).
The sound system works by creating an acoustic field around the flame, giving velocity to the air molecules. This then disrupts the flame boundary layer, where combustion occurs.
The sound waves also interfere with the pool of fuel at the base of the flame, increasing the rate of fuel vaporisation – which widens the flame and also causes the flame temperature to dip.
By fine-tuning the frequencies of the sound waves, the researchers were able to widen the flame out sufficiently and disrupt the boundary layer enough to put it out.
While the work remains little more than a proof of concept – it's not yet clear to the researchers how it could be scaled for industrial use - they hope to inspire further research.
“We have shown that the physics of combustion still has surprises in store for us. Perhaps these results will spur new ideas and applications in combustion research,” said Matthew Goodman, DARPA manager for the instant fire suppression programme.
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