DARPA Uses Sound to Extinguish a Fire

Posted on July 18, 2012

DARPA uses an acoustic field to extinguish a flame in this clip. The acoustic field generated by speakers on either side of the fire. DARAPA says two dynamics are at play in this approach to fire suppression:
First, the acoustic field increases the air velocity. As the velocity goes up, the flame boundary layer, where combustion occurs, thins, making it easier to disrupt the flame. Second, by disturbing the pool surface, the acoustic field leads to higher fuel vaporization, which widens the flame, but also drops the overall flame temperature. Combustion is disrupted as the same amount of heat is spread over a larger area.
Take a look:

DARPA also used a handheld electrode to suppress small methane gas and liquid fuel fires, see here. The research into alternative fire-suppression technologies is part of DARPA's Instant Fire Suppression (IFS) program.
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