| The vortex tube is a device with no moving parts that is capable of separating a high-pressure flow into two lower pressure flows of different temperature. Due to simple operation, reliable run, low maintenance cost and so on, the vortex tube has been found much use in many areas. But the flow and efficiency of the vortex tube are low, which severely limits the promotion of the vortex tube. While the vortex tube has the advantages of simple operation, but the mechanism of the energy separation is extremely complex. So many scholars have analyzed the mechanism of the vortex tube energy separation, but there is no precise theory can explain the reason of the vortex tube energy separation.The thesis mainly investigates the working mechanism and structural characteristic of vortex tube from two aspects of numerical simulation and testing. This lays solid foundation for improving the refrigerating effect and enlarging its applications fields.Firstly, the three-dimensional model of the vortex tube is determined in this paper. On this basis, the energy separation process and flow characteristics of the vortex tube are simulated numerical by the Fluent. The influences of inlet pressure, inlet flow and cold flow fraction on the internal flow field of vortex tube were investigated. The results that the inlet pressure and the flow had the important influence to the vortex tube energy separation effect. The cold flow fraction is the ratio of cold air flow and inlet gas flow rate, the cold flow fraction can affect the performance of the vortex tube by controlling the temperature of airflow at both outlets.Secondly, this paper also studies the key parts of the vortex tube, which is vortex generator, guide vane and regulating valve effect on the performance of vortex tube. The flow field distribution of the air flow through the swirl generator, the flow guide vane and the regulating valve is analyzed numerical simulation method. When the blade of the vortex generator is arc-shaped, the taper angle of the regulating valve is 30 °, the energy separation effect of the vortex tube is best.Finally, setting up a vortex tube performance experiment platform and amounted for the purpose of testing the performance of internal temperature field in a vortex tube. The influences of inlet pressure and inlet flow on the distributions of temperature field were investigated. And according to the measured value to calculate the cooling effect, thermal effect, refrigeration efficiency and other performance parameters of the vortex tube. The results show that the cooling efficiency of the vortex tube is gradually increased and then decreased with the increase of cold flow fraction, When the cold flow rate is 0.6-0.7, the cooling efficiency of the vortex tube reaches the maximum value, and the maximum cooling efficiency is about 21%. |
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