Numerical simulation of energy separation effect inside vortex tube

Acquisition of the temperature distributions inside the vortex tube is a principal and key problem for disclosing the fundamental mechanism underlying the energy separation effect inside the tube. The 'Realizable k-ε' turbulence model of computational fluid dynamics (CFD) was used to simulate the energy separation effect produced by three-dimensional compressible flow with strong swirl inside the vortex tube. Then the axial and radial distributions of total and static temperature were obtained. The mean kinetic energies and the stagnation enthalpies of the peripheral and inner flows per unit mass along the airflow direction were also examined respectively because the enveloping surface of zero axial velocity is the interface between peripheral and inner airflows. In order to validate the numerical results, comparisons between the numerical predictions and the experimental results were conducted for the cold air temperature drops as a function of cold fraction, and satisfactory agreements were observed. A non-dimensional strategy was adopted to compare total, static temperature distributions along the radial direction at a given axial location with the experimental data from previous studies, so the accuracy of the numerical results was further validated.