Half a croissant, on a plate, with a sign in front of it saying '50c'
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Vortex ring fan

For long distance, or outside use.
  [vote for,

Maybe you've seen those toys that send smoke rings across the room? They generate vortex rings by thumping the back of a diaphragm into a shaped chamber with a circular exit, and can blow out candles at surprising distances, because the vortex ring is highly stable.
There are military applications as well: A small charge is used to generate pressure, and the resultant vortex ring can knock a man over. The charges can be set off at 10 per second, which is apparently totally debilitating, but not lethal.
What I propose is another version, where the diaphragm is rapidly oscillated, perhaps by a sub woofer speaker.
The rapidly created vortex rings would act like highly directional cooling fans, with long distance capability. I think these might be useful in gardens or large halls.

There might be many applications for portable, high power, devices: sweeping leaves; picking fruit; pest control etc.

Ling, Nov 06 2006

Said video finds http://video.google...e&resnum=633111553#
[normzone, Jun 29 2009]

Vortex Rings Audio_20Delusionator
Cross Referenced idea [csea, Jul 03 2009]

Dolphins playing with air vortices... http://www.snopes.c...ls/dolphinrings.asp
Incredible, is the only word. [4whom, Jul 03 2009]

Wikipedia: Rotary woofer https://en.wikipedi.../wiki/Rotary_woofer
Mentioned in my anno [notexactly, Jul 11 2019]


       Yes, vortex rings are cool, but have some very real limitations, something to do with laminar/turbulent flow. Basically you can only invest a certain ammount of energy into the ring otherwise it just tears itself apart almost immediately.   

       The interesting thing is that they can be used to transport gas, ie smoke, propane (yes, go google it, all sorts of nefarious fun), cold air, etc. So maybe instead of using high power vortexes, simply use them to transport frigidly cold air, and then viola (haha) spot focus for your airconditioner.   

       One offshoot of this would be if you could run selective climate control. Different people in a room have customised air temperature settings. A computer driven set of vortex generators coupled with ho and cold air supplies will constantly fire vortexes at the recipient, continuously bombarding them with their preferred temperature (and scented?) air.   

Custardguts, Nov 06 2006

       I like your idea of transportation of cold or hot air. That's a good improvement.
Ling, Nov 06 2006

       I think I have seen this on a small scale, used to cool a pc down. I will see if I can find a link.
Chefboyrbored, Nov 06 2006

       You could get both hot and cold air from a semiconductor refrigerator (Peltier)
anchornm, Jun 29 2009

       I was pondering gas vortices and how they could propagate in a vacuum. Intravortex turbulence would still probably limit total distance. But if all the gas molecules could be aligned so that they were all travelling the same direction, a cloud of gas could travel infinitely far.
bungston, Jun 29 2009

       I was disappointed that although it is easy to find video of giant vortex ring cannons, I could not find any where the cannon was charged with flammable gas and fired at a candle. I would think that anyone owning a vortex cannon would immediately think of this, uh, "application".
bungston, Jun 29 2009

       I want one. And I'll pay with baked goods to get it.
swimswim, Jun 29 2009

       [bungston] Not everybody thinks like us. The world would be so much more... interesting... if they did.
Alterother, Jul 01 2009

       Propelled vortices rely on the boundary layer effect. Although we generally assume gasses are ideal gasses, that is seldom true in the real world. They are more lightly viscous liquids, in terms of fluid dynamics. Volatile gasses are harder to form into a vortex than air for example, remember that your smoke ring, or CO2 ring, or other, is actually just an air vortex trapping other molecules in a spinning torus, and by way of conservation of angular momentum the heavier molecules stay in the torus.   

       I have nothing against a propane votex, in an atmosphere of propane. It is just that propane vortices in air will degenerate and not propagate. You could probably have an air vortex in a propane atmosphere, but I doubt the reverse occurs.   

       That is the position of physics, but just watch that video of dolphins playing with air vortices in water, and have your mind warped.
4whom, Jul 01 2009

       I have seen video of flammable gas being shot from a vortex cannon and hitting a candle. I don't think it was on youtube. Try googling instead.   

       My home i-net is down until I replace my PC so I'm afraid I can't go searching. [Bung], have you tried making a vortex cannon? It's really easy. You can make a little one with an empty 2-litre coke bottle for gawd's sake. Just with the small aperature, you can only make small vortex rings.
Custardguts, Jul 01 2009

       There is an ancient tome that chronicles the experiments of the first man to dabble with vortex rings of his own bodily vapors using no more than a sausage casing and a sheep’s bladder. I believe his name was Marlond or Merling or somesuch.   

       A good read.
I'd highly recommend it but the monks transcribing the original took a sudden vow of illiteracy and burned the whole lot one winter...whadaya gonna do?

       //Not everybody thinks like us. The world would be so much more... interesting... if they did// [Alterother]   

       I like that! It would be a fun world one to many grammar sharks but fun
dev45, Jul 02 2009

       If the requirement is that the gas that the ring is made of, be denser than the surrounding atmosphere, then instead of trying to shoot unlit propane at a lit candle, one should try to shoot a ring of unlit heavier-than-air fuel at a lit candle.   

       So, I would expect flour or charcoal dust to work.
goldbb, Jul 02 2009

       [goldbb] That would work. And would be awesome to see (under high speed cameras). My last outstanding issue is the candle as ignition source. But that can easily be overcome, by using something else and even recently extinguished candles can ignite certain substances.
4whom, Jul 03 2009

       Some fog machines use an oil based fog. I am sure that flammable oils are generally not used in these machines because of the outrageous danger that a cloud of inflammable oil droplets would present to all nearby. But of course it would make a spectacular fire ring.
bungston, Jul 03 2009

       Awesome idea!
danman, Jul 03 2009

       It might be worthwhile (for some purpose or other) to use a rotary woofer [link] in this thing, rather than a traditional cone subwoofer.
notexactly, Jul 11 2019


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