Energy separation in fluid streams

The physical processes underlying energy separation in gases and liquids are examined with particular reference to the processes occurring in the vortex and resonance tubes. It is shown that, in the vortex tube, energy separation is primarily caused by pressure forces acting on the fluctuating curved streamlines with a minor contribution from viscous forces. The effectiveness of energy separation in the vortex tube decreases as the mass flow ratio moves toward zero or one. The vortex tube is found to be the most effective device of those considered here when a stream of cool air or cold gas has to be obtained. The resonance tube, however, is more effective in generating a gas stream of high temperature.