Numerical prediction of vortex flow and thermal separation in a subsonic vortex tube

Abstract

This work was aimed at gaining understanding of the physical behaviours of the flow and temperature separation process in a vortex tube. To investigate the cold mass fraction’s effect on the temperature separation, the numerical calculation was carried out using an algebraic Reynolds stress model (ASM) and the standard k-ɛ model. The modelling of turbulence of compressible, complex flows used in the simulation is discussed. Emphasis is given to the derivation of the ASM for 2D axisymmetrical flows, particularly to the model constants in the algebraic Reynolds stress equations. The TEFESS code, based on a staggered Finite Volume approach with the standard k-ɛ model and first-order numerical schemes, was used to carry out all the computations. The predicted results for strongly swirling turbulent compressible flow in a vortex tube suggested that the use of the ASM leads to better agreement between the numerical results and experimental data, while the k-ɛ model cannot capture the stabilizing effect of the swirl.