Study the effect of pressure on airflow field in vortex spinning nozzle by numerical simulation

Abstract

Vortex spinning technology is with the help of high speed swirling airflow to twist fibers with open ends to form the yarn. Spinning parameters, such as nozzle pressure, has a great effect on yarn properties. In this study, different nozzle pressures were researched through spinning experiments, in addition, the homologous three- dimensional computational fluid dynamics model of the nozzle was built to simulate the numerical calculation of the airflow in vortex spinning nozzle. Realizable k-epsilon model was used to simulate the turbulence of airflow in the nozzle. Unstructured tetrahedral grids which are suitable for airflow with wall effects and complicated boundary layers were adopted to divided grids in the computational area. The computational model of the airflow field was solved and the characteristics of airflow in vortex spinning nozzle was obtained. Through the results of numerical simulation, the corresponding airflow field within the nozzle was analyzed which provides reference for setting of spinning parameters. The numerical simulation results show that the velocity vector and the static pressure increase with the nozzle pressure, the principle of the swirling airflow is decided by the pressure distribution, a large negative pressure with appropriate axial and tangential velocity within the nozzle is conducive to the generation of the fibers with open ends and the twist. Spinning experiment results showed that the optimum nozzle pressure is 0.5-0.6Mpa, which shows a good agreement with the numerical simulation results.