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Temperature and Pressure Measurements at Cold Exit of Counter-flow vortex tube with Flow Visualization of Reversed Flow

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Journal of Thermal Science 2015年第1期24卷 67-72页

作者： Mohd Hazwan bin Yusof Hiroshi Katanoda Hiromitsu Morita Graduate School of Science and Engineering Kagoshima University National Institute of Advanced Industrial Science and Technology Hokkaido

In order to clarify the structure of the cold flow discharged from the counter-flow vortex tube(VT), the temperature and pressure of the cold flow were measured, and the existence and behavior of the reversed flow at the cold exit was studied using a simple flow visualization technique consisting of a 0.75mm-diameter needle, and an oil paint droplet. It is observed through this experiment that the Pitot pressure at the cold exit center can either be lower or higher than atmospheric pressure, depending on the inlet pressure and the cold fraction, and that a reversed flow is observed when the Pitot pressure at the cold exit center is lower than atmospheric pressure. In addition, it is observed that when reducing the cold fraction from unity at any arbitrary inlet pressure, the region of reversed and colder flow in the central part of cold exit extends in the downstream direction.

关键词： vortex tube Reversed flow Flow visualization Pressure measurement Temperature measurement

Numerical prediction of vortex flow and thermal separation in a subsonic vortex tube

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第8期7卷 1406-1415页

作者： SMITH Eiamsa-ard PONGJET Promvonge Department of Mechanical Engineering Faculty of Engineering Mahanakorn University of Technology Bangkok 10530 Thailand Department of Mechanical Engineering Faculty of Engineering King Mongkut's Institute of Technology Ladkrabang Bangkok 10520 Thailand

This work was aimed at gaining understanding of the physical behaviours of the flow and temperature separation process in a vortex tube. To investigate the cold mass fraction’s effect on the temperature separation, the numerical calculation was carried out using an algebraic Reynolds stress model (ASM) and the standard k-ε model. The modelling of turbulence of com-pressible, complex flows used in the simulation is discussed. Emphasis is given to the derivation of the ASM for 2D axisymmet-rical flows, particularly to the model constants in the algebraic Reynolds stress equations. The TEFESS code, based on a staggered Finite Volume approach with the standard k-ε model and first-order numerical schemes, was used to carry out all the computations. The predicted results for strongly swirling turbulent compressible flow in a vortex tube suggested that the use of the ASM leads to better agreement between the numerical results and experimental data, while the k-ε model cannot capture the stabilizing effect of the swirl.

关键词： vortex tube Cold mass fraction Swirl fiow Temperature separation Flow field

Three-Dimensional Numerical Investigation of the Separation Process in a vortex tube at Different Operating Conditions

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Journal of Marine Science and Application 2016年第2期15卷 157-165页

作者： Seyed Ehsan Rafiee M.M. Sadeghiazad Department of Mechanical Engineering Urmia University of Technology Urmia P.O. Box 57155-419 Iran

Air separators provide safe, clean, and appropriate air flow to engines and are widely used in vehicles with large engines such as ships and submarines. In this operational study, the separation process in a Ranque-Hilsch vortex tube cleaning （cooling） system is investigated to analyze the impact of the operating gas type on the vortex tube performance; the operating gases used are air, nitrogen, oxygen, carbon dioxide and nitrogen dioxide. The computational fluid dynamic model used is equipped with a three-dimensional structure, and the steady-state condition is applied during computations. The standard k-c turbulence model is employed to resolve nonlinear flow equations, and various key parameters, such as hot and cold exhaust thermal drops, and power separation rates, are described numerically. The results show that nitrogen dioxide creates the greatest separation power out of all gases tested, and the numerical results are validated by good agreement with available experimental data. In addition, a comparison is made between the use of two different boundary conditions, the pressure-far-field and the pressure-outlet, when analyzing complex turbulent flows in the air separators. Results present a comprehensive and practical solution for use in future numerical studies.

关键词： vortex tube air separator separation process operatinggas numerical simulation