Numerical simulation of the effect of flow field in swirl nozzle spinning on yarn performance

Abstract

Swirl nozzle spinning is an effective method to reduce ring-spun yarn hairiness due to device structure and vortex characteristics. This study establishes a computational domain of a swirl nozzle comprising an air inlet channel and a yarn channel to investigate the characteristics of the vortex in the swirl nozzle and the effects of inlet pressure on the wrapped force of the yarn. Simulation results show that the airflow rotates clockwise toward the two yarn entrance directions; moreover, the pressure at the central area of the yarn channel is lower than that of the surrounding area, which is good for the yarn’s steady movement and free fibers wrapping on the yarn surface into the yarn body. When the inlet pressure is high, the pressure spreading to each section of the yarn channel is also high. When the difference between the pressure near the inner wall and the yarn axis is high, the yarn surface has added high pressure, and the velocity and its fluctuation are also high. Experiment result reveals that 0.2 MPa is sufficient in significantly reducing yarn hairiness and that operating the nozzle under a low air pressure is economical. Thus, the numerical simulation can provide the theoretical as well as quantitative reference for the vortex tube design in the coming future.