Study On Energy Separation Characteristics As Well As Its Mechanism Of A Vortex Tube

As a simple energy separation device,vortex tube can achieve refrigeration,heating and temperature separation effect,has been widely used and has great development potential in the refrigeration,cryogenic organisms,precision instruments,aviation and many other fields due to its convenience of use,but the low efficiency of energy separation effect is the bottleneck that limits the further application of vortex tubes.Understanding the flow pattern inside a vortex tube has an important guiding significance for the cognizance of the temperature separation mechanism of a vortex tube.However,at present,the theoretical research on the vortex tube has been seriously lagging behind.Due to the lack of reliable theoretical models,the prediction of the trend of energy separation effects caused by vortex tube structure and operating conditions becomes extremely challenging.It is urgent to find an effective method to predict the energy separation and flow behavior in the vortex tube,to understand the flow mechanism in the vortex tube,to guide the improvement of the vortex tube structure and the optimization of performance,and to promote its wider application.Under the guidance of this idea,the following research work were mainly carried out in this paper:1?An innovative mathematical calculation model for vortex tube performance was established.The research idea of dynamic partition modeling of the vortex tube was firstly proposed and the expression of dynamic counterflow boundary?which separates the fluids flow to the hot and cold end was established in this model.The countercurrent boundary?changes with the change of cold flow ratio?_c and the outlet pressure ratio of the hot and cold endp_h/p_c.Based on the dynamic counterflow boundary?,different dynamic regions were devided.A set of mathematical models considering the influence on the distribution of internal fields in the vortex tube was established for the first time.The distribution of the three-dimensional velocity fields inside the vortex tube under different working conditions were analyzed and predicted.Based on the dynamic countercurrent boundary,the heat and energy transfer processes between different regions were analyzed,and the mechanism of the separation of working fluid energy in the vortex tube was clarified.2?The experimental device for measuring the energy separation characteristics of the vortex tube was built.The five-hole probe and thermocouples were used to obtain the total pressure,static pressure,total velocity,the three-dimensional velocity fields of the vortex tube at different axial positions and different radial positions.The distribution law,and the influence of relationship between the cold mass flow ratio and the flow fields inside the vortex tube were explored.Different from the traditional view that the tangential flow inside the vortex tube was similar to the identification of the Rankine vortex,it was considered that the steady-state tangential vortex flow was more consistent with the steady Burgers vortex form.By calculating the energy transfer process inside the vortex tube,it was concluded that the vortex tube separation was mainly the combined results of action of tangential momentum transfer,axial momentum transfer and thermal conduction.The momentum transfer was mainly transmitted from the inner layer fluid to the outside.The thermal conducted from the inside layer to the outer region near the nozzle outlet,with the fluid flows toward the hot end the thermal conduction gradually changed from the outer side to the inner side.3?The CFD numerical simulation technology was used and a three-dimensional model of the vortex tube was established,the appropriate regional coupling boundary conditions were set and the flow fields were calculated.Through exploring the internal temperature field,velocity field and pressure field of air flowing in the vortex tube,the comparation and verification of the simulation results with the proposed theoretical model and experimental results were conducted and further understanding of the energy separation effect of the vortex tube was explained.This project has great significance in scientific research and practical application,especially for correct understanding of the energy separation mechanism and the improvement of energy separation efficiency of a vortex tube.