3D numerical analysis on the effect of rounding off edge radius on thermal separation inside a vortex tube

Abstract

Vortex-chamber is a main part of vortex tube which the pressured gas is injected into this part tangentially. An appropriate design of vortex-chamber geometry leads to better efficiency and good vortex tube performance. In this study, the computational fluid dynamics (CFD) model is created on basis of an experimental model and is a three-dimensional (3D) steady compressible model that utilizes the k-ε turbulent model. In this paper the effect of changing radius of rounding off edge at hot tube entrance (r1) on vortex tube performance has been studied for different value of r1 and the optimized radius has been determined. According to numerical results the cold temperature difference has increased when we take into account the effect of the radius of rounding off edge in the range of 0-1.5 mm and when the radius of rounding off edge has located in the range of 1.5-4 mm, the cold temperature difference has decreased. The highest ΔTc is 47.26 K for r1=1.5 mm at a cold mass fraction of 0.3, higher than basic model around 7.5% at the same cold flow fraction. Finally, the results obtained, particularly the temperature values, are compared with some available experimental data, which show good agreement.