New Dual Vortex Tube Performance

Vortex tube is a new device that separates a compressed gas into cold and hot streams simultaneously, which makes it especially attractive for applications in scientific research and industry. However, its disadvantage of low efficiency and less refrigerating output limit its more extensive applications. So far, most of the researchers have been concentrating on single-circuit vortex tube, whereas investigations of double-circuit vortex tube have seldom been involved.The thesis mainly investigates the working mechanism and structural characteristic of double-circuit vortex tube from two aspects of numerical simulation and testing. This lays foundation for improving the refrigerating effect and enlarging its applications fields.Firstly, the 3-D geometry model of the double-circuit vortex tube is determined based on the designing experience and methods in the single vortex tube. On this basic, the interior fields of the double-circuit vortex tube are simulated numerically using the Fluent 6.0. and the pattern of flow streamlines is obtained. The distributions of tangential velocity, axial velocity, radial velocity and total temperature, static temperature are respectively analyzed. Simultaneously, the correctness of the numerical simulation is verified through comparing the tangential velocity, axial velocity, total temperature, static temperature distributions with Bruun's and Gao's experimental results based on the dimensional analysis.Secondly, the effects of the operating and structural parameters on the performance of the double-circuit vortex tube are investigated, which consist of the cold mass flow, the main inlet pressure, the additional inlet pressure, the diameters of the additional-circuit and the length of the hot tube have an important effect on the double-circuit vortex tube refrigeration effect.Finally, the double-circuit vortex tube is designed and the structural parameters are determined based on the numerical geometry parameters and emulational parameters. An experimental platform established and the influences of parameters mentioned above on the performance of the double-circuit vortex tube are researched. The effect tendency and optimized values are obtained. The refrigeration effect of the double-circuit vortex tube is better than that of the single vortex tube with a certain region cool mass fraction. Meanwhile, the double-circuit vortex tube has the same performance as the single vortex tube in the case that the additional inlet is closed. And then the experimental results coincide well with the numerical values.