Numerical investigation of energy separation in a low pressure vortex tube under different axial angles of injection nozzles

In this article، effect of axial angle of injection nozzles on the flow field structure in a Low-Pressure vortex tube has been investigated by computational fluid dynamics (CFD) techniques. Numerical results of compressible and turbulent flows are derived by using the standard k-ε turbulence model. The dimensions of studied vortex tubes are kept the same for all models and the performance of machine is studied under 6 different axial angles (β) of nozzles. Achieving to a minimum cold exit temperature is the main goal of this numerical research. Our investigation shows that utilizing this kind of nozzle changes the energy separation and flow characteristic. Considering total pressure of cold flow، a new parameter، ξ is defined and results shows that changing the amount of ξ can affect the cold exit temperature directly. Finally، some results of the CFD models are validated by the available experimental data which show reasonable agreement.