Effect of convergence angle of Ranque-Hilsch vortex tube on the optimization of thermal separation in compressible swirl flow

Ranque-Hilsch vortex tube is a highly efficient fluidic expansion device with thermal separation features. Geometric optimization of the device is necessary for getting the best performance. Current study aims to conduct a validated and comparative analysis of the significance of angle of convergence in a convergent vortex tube compared to a straight tube design. Numerical simulations of the swirl flow field are performed to maximize thermal separation. The result shows a strong correlation between swirl flow intensity distribution and vortex tube convergence angle, suggesting that adjusting the angle can remodel vortex core to improve temperature separation. The occurrence and analysis of the bifurcation point confirm the critical angle of convergence, where optimal temperature separation occurs most effectively and efficiently. Exergy and enthalpy-entropy analyses validate the design features, indicating a reduction in cold exit flow irreversibility when the design features critical convergence angle. Further studies are warranted for a comprehensive optimization of the design.