Three Dimensional Simulation Of The Interior Field Of Vortex Tube And Performance Analysis

The vortex tube is a device,it can easy to maintain,portable and requires only high pressure gas to achieve hot and cold separation.The vortex tube has been widely used in refrigeration,vacuum,chemical and biological fields because of the unique operating characteristics.The internal flow of the vortex tube is particularly complex and the performance differences of the vortex tube are ralated to many factors,so,it is basic for expanding the application of the vortex tube that correctly understanding the fluid flow state inside the vortex tube and the influence factors of the performance.In this paper,based on the Fluent numerical simulation,the pressure field,temperature field and three-dimensional flow field in the vortex tube are simulated by R41.And the optimum working fluid in various refrigerants working fluids was studied to study the effects of operating parameters and structural parameters on the cooling effect,heating effect and separation effect of vortex tube.The simulation results show that there are obvious pressure gradients and temperature gradients inside the vortex tube,and the pressure and temperature from the axial region to the outer edge region gradually increase on the hot end tube shaft section.The pressure gradually decreases from the vortex chamber to the hot end valve,but the trend of the tempresure is opposite.Simulation analysis show that there are three-dimensional flow states inside the vortex tube,and it has there characteristics,positive swirling flow and reverse swirling flow,secondary circulation flow,free vortex and forced vortex flow.The axial velocity has a directional transition at the boundary point between the positive swirling flow and the reverse swirling flow when the radial distance increases as the hot end tube axial section increases;the radial velocity has a Transition from the inside out because of secondary circulation flow;the trend of tangential velocity is increase first and then decrease,the peak point is the turning point of the free vortex and the forced vortex,and its value is 110m/s.The axial velocity of the fluid in the axial region gradually increases as the axial distance of the hot end tube increases,but the axial velocity of the fluid in the outer peripheralregion is opposite.Radial velocity and tangential velocity are related to axial velocity and all decrease with increasing axial velocity.The influence of operating parameters on the performance of vortex tube is mainly studied from five aspects: working fluid type,cold flow rate,expansion ratio,hot and cold pressure ratio and hot cooling pressure ratio.The results show that the influence of different working fluids on the performance of vortex tube successively is R41,R32,R23,R290,R134 a,R1234yf,and the vortex tube separation effect can reach up to about 5.3K when the working fluid is R41.the cooling effect of the vortex tube is decreases as the increase of cold flow rate,but the heating effect and separation effect of the vortex tube are opposite.When the cold flow rate is 0.7,the vortex tube separation effect is effective,and its value about 7.2K;When the cold flow rate is constant,the performance of the vortex tube increases as the expansion ratio increases.When the expansion ratio is 1.8,the heating effect of the vortex tube can reach 17K;When the inlet pressure is constant,the cooling effect of the vortex tube and the heating effect of the vortex tube increase as the increase of the cold and hot pressure ratio,and decrease as the increase of the hot and cold pressure ratio.The influence of structural parameters on the performance of vortex tube is mainly studied from three aspects: nozzle number,nozzle shape and hot end tube length.The results show that the influence of different nozzle numbers on the performance of vortex tube successively is 3 channel,2 channel,4 channel,5 channel,6 channel when the inlet pressure and cold flow rate are constant,the maximum cooling effect is about 4.25 K and the maximum heating effect is up to 4.6K when nozzle number is 3 and the performance of different nozzle shape vortex tubes successively is tapered nozzle,linear nozzle,Archimedes nozzle.When the cold flow rate is 0.7,the tapered nozzle separation effect is about 0.7K higher than the linear nozzle separation effect,and about 0.9K higher than the Archimedes type nozzle separation effect;when the inlet pressure and cold flow rate are constant,and the length of the end tube is 100 mm,the performance of the vortex tube is the effective,and the maximum separation effect is up to 3.7K.