This is a video of DARPA's latest alien technology, a sonic fire extinguisher (just kidding, it's actually just two speakers). It puts fires out with sound. Me? I've actually seen a fire MADE with sound before. I'm serious, one time my buddy held a lighter to back of his sweatpants and "PPPPPWT!", a stinky fireball. I think he's a wizard.
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.
Hey, not to brag or anything but I've put out a fire out with sound before. The sound of a fire-extinguisher being sprayed! HIYO, I'm clever.
Hit the jump for the video.
Thanks to Cameron, who puts out fires the old fashioned way: yelling "OH SHIT, OH SHIT, OH SHIT!" and fanning it with a towel until it actually gets bigger and you have to call 911.