Analysis of energy separation inside a Ranque-Hilsch vortex tube using RANS based CFD
Karthik Vigneshwar Cuddalore Balakumar, Peter J. Disimile
Abstract
The primary aim of this study was to investigate the role of turbulent structure in energy separation inside Vortex Tube. The important flow features were identified using RANS based CFD. The flow was divided into two parts above and below the cross-over region which is the radial location where the axial velocity is zero i.e., the flows above and below this region are oppositely directed. The Reynolds stress analysis revealed the stresses to be maximum at the cross-over region. In addition, the reversing and expanding core flow was found to have a temperature drop greater than that computed assuming an isentropic expansion process. This was also confirmed in the Control Volume (CV) analysis of the energy in the core flow wherein the core flow at the outlet of the CV was found to have experienced an energy loss compared to when it entered the CV. This was then correlated with the assumed work and heat interactions across the control surface bounding the CV of the core flow. The energy difference in the core flow computed by the two methods were found to agree within an accuracy of 10 %, thus validating our assumptions regarding the presence of heat and work transfer between the core and annular flows. The analysis also revealed that the turbulent shear work to be the dominant mode of energy transfer between the core and annular flows, comprising about 80 % of the energy transfer, and remaining 20 % attributed to heat transfer.