Vortex tube as acoustic standing wave explanation

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rentier
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I have an interesting(IMHO) approach to explaining how the vortex tube works.
There are a few explanations on wiki, but not a simple and convincing final one.
https://en.wikipedia.org/wiki/Vortex_tube

Normally a vortex tube, that runs well, howls very loud.
It is a kind of aerodynamically peculiarly shaped, twisted and folded "flute" (tangential air inflow, etc.), i.e. standing acoustic wave. If we have an outlet nozzle at the anti-node, more air comes out at higher pressure, adiabatically compressed, i.e. warm, and in periods of lower air pressure, there is less flow of the colder air. I.e. on average, more warmer air comes through.
Therefore the remaining air that flows further (or back, in the middle) is net colder.
The rotation, the spiral-shaped flow, essentially increases the length of the "flute", i.e. affects frequency.

(this could be verified experimentally in a linear assembly, I think.)

  • Is it a sane approach?
  • Does a vortex tube work, if the return flow goes through an additional insulated central tube? (guess yes)
 
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