A comparison of the application of RSM and LES turbulence models in the numerical simulation of thermal and flow patterns in a double-circuit Ranque-Hilsch vortex tube

The present paper reports an investigation of a double-circuit Ranque-Hilsch vortex tube using a fully three-dimensional numerical model of the turbulent compressible air flow. The main purpose of the paper is to perform a detailed analysis of the thermal and flow patterns obtained with RSM-LRR and LES turbulence models in order to understand which one is able to represent the Ranque-Hilsch energy separation effect observed in a double-circuit vortex tube in the most effective way. The LES turbulence model is found to represent the qualitative turbulence of the flow better than the RSM-LRR model. The detailed analysis of turbulence characteristics estimated by LES model indicates that turbulence has a significant impact on the energy separation phenomenon. Both LES and RSM-LRR turbulence models are shown to have a weak accuracy in the prediction of the integral characteristics of a double-circuit vortex tube. An attempt was made to improve the results achieved with LES turbulence model by means of a grid refinement and an increase of Smagorinsky constant value, but they were found to have a limited impact. This leads to the conclusion that more advanced kinds of LES turbulence model should be investigated in order to increase the accuracy of the simulation of a double-circuit vortex tube.