Two engineering students from George Mason University have built a rather unorthodox fire extinguisher. It uses a subwoofer to send sound waves powerful enough to extinguish small fires.
Similar in concept to a giant smoke-ring canon, the device uses a subwoofer with a tube that has a smaller aperture opening at the end. When the bass drops (literally), this causes an intense wave of sound (well, air), to be expelled from the device. And as you can see in the video below, it’s quite effective at putting out small fires.
They use a small frequency generator and amplifier to power the system, and throughout extensive testing found 30-60Hz to work best. It’s not actually one big blast of air, but a pressure wave that goes back and forth — agitating the air, and separating it from the fire. There is a catch though.
One of the problems with sound waves is that they do not cool the fuel,” Isman said. “So even if you get the fire out, it will rekindle if you don’t either take away the fuel or cool it.
[Robertson] and [Troy] started the project as their senior research work, but are now planning to continue developing it for commercial potential. They applied for a provisional patent in November and continue testing the device on different types of fires.
[via Adafruit]
First thought: for that subwoofer this is near-field, so it is essentially wind that is putting out the fire.
It actually works by increasing the rate of evaporation of the fluid, which makes the A/F mixture near the surface too rich and that snuffs the flame.
Would it even work in a forest fire then? A forest isn’t a liquid fuel like they show here.
No.
this is why the airborne dubstep woofer should also contain a fuel spray: spray fuel on burning forrest, then use subwoofer to evaporate the fuel around the forrest so as to snuff out the combined forrest+fuel bonfire…
Put it in hoods over the stove.
Hook it up to an ionizing smoke detector to trigger it.
Put out the fire with out ruining the food (well any more than flames already ruined it).
If it’s just air won’t it spread the fire?
Its just air, but it is not wind. Wind blows and spreads fire. This is an alternating pulse of air, moving back and forth quickly. There is no net-movement of the air (aka no wind), and thus no spreading of the fire.
You can think of it like shaking the crap out of all of the air molecules around the fire, so that they cannot burn
Like shaking a lit match in reverse :)
Maybe some interesting applications here with phased arrays that could “target” fire in an enclosed space without the need to carry the “extinguisher” around– something like a sprinkler system but without the water.
I’m not sure this will ever be viable for anything but very small fires, though.
Still, a fun project.
I was thinking that exactly. The obvious application is built-in phased array located above the cooktop in a restaurant or home. I wonder how a flame would behave in the field generated by the last acoustic phased array thing we saw come through…
http://hackaday.com/2014/01/03/3d-acoustic-manipulation-seeminly-unreal-levitation-using-soundwaves/
Use a fire blanket, is cheaper, is always ready and it works.
yeah, why should someone bother to use new technologys for old problems! Just rediculous…
Your grammar is ‘rediculous’:
technologys -> technologies
problems! -> problems?
rediculous -> ridiculous
Spelling, not grammar. Muphry’s law.
I see what you did there… B^)
Grammar includes spelling and punctuation… Muphrys Slaw
Advantages ? but here I can’t see any (as fire extinguisher), they just light up/extinguish a small quantity of alcohol, it’s big, heavy, depends on power, isn’t efficient, is loud, doesn’t cool down…
What I dislike: it’s just a show to draw attention, the physical principe they use is very interesting, but they have to find an application for it, that is worth.
I’m not so harsh, when asked “What is it (hot air balloon) good for?” Ben Franklin supposedly replied,
“What good is a newborn baby?”
A nice quote but quite stupid. A newborn baby has virtually limitless future potential. They could cure cancer or save lives. A hot air balloon has a very VERY limited potential.
But you can’t “stream the hottest sick beats”* to a fire blanket.
*I have been acquainting myself with modern street vernacular. I’m told it is quite the radical scene, daddio.
Awesome. I’ve just learned that a fire blanket will put out a small fire. That’s why I come here!
I do know someone who was using a soup ladle to extinguish her smouldering mattress !
Interesting just not sure how useful it would be when it comes to forest fires especially if mounted to a drone. Any fire that would be small enough for a drone would likely be easily contained with conventional methods. Any fire large enough to warrant unconventional methods is going to be large enough that a drone wouldn’t really be able to get near it especially if it was carrying something that large.
They might make decent cleanup drones after a fire is contained assuming they where sufficiently autonomous to patrol around the outskirts of a fire looking for small upstarts that were missed. Then again since it uses sound and air to extinguish fires I would be concerned that there would be a chance that something like this might inadvertently stoke an ember while attempting to extinguish another small fire. I would really like to see how it preforms in a much less controlled test.
in a forest fire that thing would simply melt :)
For small fires its a nice idea.
That’s what I was thinking. A forest fire generates a lot of heat in the air, probably enough to auto-ignite the cone of the speaker.
Well if you want to put out forest fires (only you can stop forest fires by the way, I’m busy) you need to adapt this to a firef ighting role.
http://en.wikipedia.org/wiki/German_WW_2_Sonic_Cannon
Hey they both use infrasound and this is sound cannon is way cooler!
The good ol’ fire tetrahedron. Remove one of the elements and the whole thing collapses.
it actually doesn’t use sound, it uses infrasound between 30 and 60 Hz. you can’t hear it and dubstep wont save you.
those are very audible frequencies, just like you can hear a transformer hum at 60hz
a pure sine wave at a frequency this low is hard to hear(has to be very loud)…
The “transformer hum” contains a lot of harmonics from various crap, THAT is what we mostly hear…
http://en.wikipedia.org/wiki/Infrasound check your facts before pontificating. Low E string on a bass is 41.204 Hz fundamental frequency, last time I checked my bass was producing sound down there.
Hell yeah, that’s awesome that this is getting coverage. These guys were/are in my classes.
i recall DARPA doing something similar back in 2011. http://www.wired.com/2012/07/wall-of-sound-fire/
To extinguish forest fire? Seriously? Stupid idea. The burning wood is too hot. You can maybe blow out the flames. But after seconds, it will start burning again. You have to cool down the wood to kill the glow. Water is the easiest way and cheap.
BTW: Flying over a burning forest will kill the drone. Way to much heat for plastics, electronics and accu.
You can maybe extinguish burning fat in your pan. But a fire blanket is cheap and do not need any energy source.
It isn’t just the heat, fires of a sufficient size can also generate their own wind. Which would be problematic for a drone. Assuming it hadn’t melted by then :P
This would be a great way to extinguish fires in space. Most current methods of putting out open fires do so by removing oxygen from the area, usually by generating a lot of gas to smother the fire. Not exactly the most optimal approach in a closed tube where you still plan to breathe that air.
That all really depends on the source of the fire. If the fire is standalone without any significant contributing fuel source, it could probably work. Then you move into the whole do you want to take the chance with probably or do you want to vent the compartment and be 99.987% sure it is out.
Don’t fires in space tend to be self extinguishing? Without gravity combustion products hang around the fire eventually smothering it.
no thermal convection takes care of those
Drunken German saying: Alles hat ein Ende, nur die Wurst hat zwei.
Firefighter use IFEX.
It’s not a dubstep drop, it’s a one-note bass hit. The drop in a dubstep track is the entire sequence where a slow kick and snare pattern begins and synthesized “Wobbles” start in rapidly changing amplitudes. Try to put out a fire with a Zomboy track, sh*t’s straight fire its own right.
I like this idea. And I like that these guys have got some publicity. But I don’t like the fact that what is basically a nifty science experiment is suddenly a million dollar startup idea that must be patented and stuck on drones! As others have said, this is great for pan-fires and a few other niches (which all have cheaper and more reliable solutions anyway) but looking at it critically it will simply never work for anything like a large forest fire. Even extinguishing burning charcoal would probably be hard for this thing – the only place it works is burning fuels where a flame is needed to re-start the burn, and the flame is relatively small so it can be entirely removed by the machine.
I wish we lived in a world where anyone discovering an effect like this documented it, tried some experiments, encouraged others to do the same and moved on without seeing $$$ signs everywhere :)
What we have here gentlemen is a solution looking for a problem.
…and if the battery dies, they could probably just smother the pie plate fire with the speaker enclosure… B^)
“The roof, the roof, the roof is on fire…we dont need no warer, let the subwoofer drop hertz. Drop hertz, subwoofer, drop'”
I’m pretty sure it work by using a standing wave to prevent the fire exhaust from escaping. The fire then smothers itself.