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Is this bladeless air flow idea possible in theory?

Discussion in 'General Discussion' started by Radiation, 10 May 2010.

  1. Radiation

    Mobster

    Joined: 12 Oct 2003

    Posts: 4,030

    I was just thinking about this idea again after seeing the dyson bladeless fan thread, we know air is full of moving molecules and atoms bouncing around in all directions, well what if you could get them to all move in the same direction?

    I was thinking a specially designed surface and enclosure, perhaps down to micro scales at just the right angles, it would start to control some of the ones that hit at the right angle and create a general flow in one direction.
     
  2. Tefal

    Capo Crimine

    Joined: 30 Jun 2007

    Posts: 66,716

    Location: Wales

    the dyson still uses a fan(well impeller iirc)

    But there is a solid electrical one that still has "fins" but no moving parts.

    [​IMG]


    http://www.physorg.com/news125057974.html


    chimney? As long as the air is warm/hot it will make a draft :p
     
  3. manic_man

    Mobster

    Joined: 18 Oct 2002

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    Location: Greater Manchester

    So you are saying can we make a jet and control the flow of air using the science of aerodynamics?

    if so, then yes we can, it's just quite tough to get the air to all go in the direction you want it to, unless its all occurring inside a totally sealed vacuum or over a VERY short distance. Turbulence is a bitch :)

    While I'm guessing this is just a random thought (I have those), I was wondering what you were thinking of in terms of application? If it is a replacement for computer fans and things, I would suggest that perhaps simply replacing the blades with jets of air would be fairly difficult to achieve, certainly no easier than a bladed fan and almost certainly much noisier and more complex.

    Effectively what you want to do is create a vortex induced vacuum effect at a localised spot in a computer case (which is what a fan effectively does), while its interesting, *something* still has to be moving to do this, be it the nozzles generating a high pressure air jet, or the blades of a fan moving the air around them, EDIT or the "blade-less" Dyson fan you referred to initially.
     
  4. bigsharn

    Hitman

    Joined: 25 Oct 2009

    Posts: 576

    Location: York

    I doubt very much if you could pull it off, you'd need some sort of directional push and the only ways to do that without a central motor (afaik) are to use magnets or have it on a cogwheel/belt-driven system.

    The former is a bad idea when surrounded by other electrical equipment and having no shielding and the latter being a bad idea if you're wanting to save space (as I assume you would).
     
  5. Radiation

    Mobster

    Joined: 12 Oct 2003

    Posts: 4,030

    I was thinking on the small scale using natural air movement, when the gas particles hit specially design micro channels they bounce back and forth between the sides and eventually move in one direction out the end so creating a air flow.

    Edit: im talking no moving parts, just the right design and shape that gets the tiny motions of gas (pressure) to all start going in the same direction!
     
    Last edited: 10 May 2010
  6. Tefal

    Capo Crimine

    Joined: 30 Jun 2007

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    Not going to happen really. (

    and even if you do manage it the amount of air flow will be so small that it would be over ridden by any disturbance in the air or pressure change.
     
  7. manic_man

    Mobster

    Joined: 18 Oct 2002

    Posts: 2,954

    Location: Greater Manchester

    How are you going to control the initial direction of flow of each particle? Even if you can "trap" them in a channel (how do you allow for the effects of restitution / friction etc?) and make them "bounce" from side to side, given just how many particles we are talking here, some will have an initial momentum meaning they will travel one way down the channel, others will go the other way, while there is a chance others still will simply not travel in either direction and bounce between each side of the channel until entropy does its work.

    All of this is also an incredible over-simplification of what we are actually talking about here, my description works IF you consider the component particles of air to be little spheres floating about in space... clearly that's not a reasonable model to actually work with in reality...

    Aside from the fact that generating channels that small is one heck of an engineering feat!
     
  8. Strife212

    Capodecina

    Joined: 15 Dec 2007

    Posts: 16,574

    Doesn't this idea violate the second law of thermodynamics :D
     
  9. Radiation

    Mobster

    Joined: 12 Oct 2003

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    One end will be different in design to the other, the difference should create an overall effect which makes the air go the way you want even though there's a lot of randomness, even a tiny difference should in theory cause air to flow, it just takes the right design.

    I don't think so as you're using the energy that already exists and just making it add up and go where you want, though i know entropy is a problem, i don't think it should be here.
     
    Last edited: 10 May 2010
  10. Solaris

    Wise Guy

    Joined: 31 Oct 2006

    Posts: 1,956

  11. kinobestew123

    Wise Guy

    Joined: 6 Feb 2008

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    I think this is where the idea starts to go wrong. The only simple way I can think of to explain it is using a snooker/pool table. Imagine the cushion on the table is your "micro-scale/fin", and the balls are air particles.

    If you were to roll a load of balls (air particles) in one direction and bounce them off this cushion, they would of course keep going in that same direction. The problem comes when the balls are hitting the cushion from all directions, they will simply bounce off and keep going in all different directions. Ones that hit perpendicular will come back in the same direction they came from. No matter how small your "fin/scale", this will still happen.

    Unless the fin was able to know which way the next particle was goin to hit from and adjust to fire it off in the same direction, it wouldn't be theoretically possible.

    Edit: Quick answers above saying the same thing in a more scientific way me thinks.
     
    Last edited: 10 May 2010
  12. Radiation

    Mobster

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    Isn't a funnel like shape at one end enough to get some difference going and movement?

    That may be too simplistic but we're dealing with tiny scales so who knows how the gas will behave, it may be that enough bouncing is going on that at any moment the difference is great enough that the gas will flow out the end and create a constant net effect.
     
  13. Tefal

    Capo Crimine

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    problem is for every 1 particle that bounces "down" the channel there will be another particle bouncing up it.
     
  14. Radiation

    Mobster

    Joined: 12 Oct 2003

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    I know thats what i thought at first but the magic should come in the difference, if the out is smaller than the in and designed different to deflect away while the in side allows for more to enter, it should flow.
     
  15. Tefal

    Capo Crimine

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    but there would be no way to make the difference.

    There are so many and all going in random directions that you could never produce a over all net drift.


    Your channels could only ever be designed to channel particles coming from a very narrow range of angles and speeds for every one that hit it just right to be sent down there would be millions of miss hits and some going the exact opposite way.
     
  16. Col_M

    Mobster

    Joined: 17 Jan 2005

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    Location: London

    A pulse jet has no blades yet creates a good bit of airflow, makes a teeeeeeny bit of noise though and gets a bit warm. Makes it pretty much useless for a fan although you could use a small one with a nicely insulated handle for a hairdryer :D
     
  17. Radiation

    Mobster

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    Yeah it's quite a problem, i doubt that it would work well even if it did.
     
  18. Tefal

    Capo Crimine

    Joined: 30 Jun 2007

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    Location: Wales

    still uses an external power source not just passive shaping :p