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Things about vortex tube :P

  1. Oct 11, 2012 #1
    this is written in wiki:
    "There are different explanations for the effect and there is debate on which explanation is best or correct.

    What is usually agreed upon is that the air in the tube experiences mostly "solid body rotation", which simply means the rotation rate (angular velocity) of the inner gas is the same as that of the outer gas. This is different from what most consider standard vortex behavior — where inner fluid spins at a higher rate than outer fluid. The (mostly) solid body rotation is probably due to the long time which each parcel of air remains in the vortex — allowing friction between the inner parcels and outer parcels to have a notable effect.

    It is also usually agreed upon that there is a slight effect of hot air tending to "rise" toward the center, but this effect is negligible — especially if turbulence is kept to a minimum.

    One simple explanation is that the outer air is under higher pressure than the inner air (because of centrifugal force). Therefore the temperature of the outer air is higher than that of the inner air.

    Another explanation is that as both vortices rotate at the same angular velocity and direction, the inner vortex has lost angular momentum. The decrease of angular momentum is transferred as kinetic energy to the outer vortex, resulting in separated flows of hot and cold gas.

    can anyone explain it for me?

    i can't understand the first explanation, i knew the the air tempreture will get higher when being compressed, but while the compressed air be released into normal pressure won'it cool down the surrounding air? In the other way, when the low-pressure air that located in the center be released, won't it affect the air near by and let the tempreture become higher?

    i totally can't understand the second explanation, i don't know how can the lost angular momentum been transfered to kinetic energy ...

    THANK U :)
  2. jcsd
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