Numerical simulation of the three-dimensional flow field in four pneumatic compact spinning using the Finite Element Method

Abstract

Pneumatic compact spinning is one of the most widely used compact spinning systems, which is achieved by utilizing airflow condensing equipment to condense fibers in bundle and improve yarn properties. Therefore, research on flow field in the condensing zone is always the emphasis and difficulty for pneumatic compact spinning. In this paper, the three-dimensional flow field of four different kinds of pneumatic compact spinning systems, including two types of roller-type compact spinning, namely compact spinning with a perforated drum and compact spinning with a groovy drum, and two types of lattice apron-type compact spinning, namely three-line rollers compact spinning and four-line rollers compact spinning, are investigated using the Finite Element Method. Firstly, four three-dimensional physical models of the condensing zone are built by AutoCAD software respectively according to the measured geometric parameters of practical condensing zones. Then, using ANSYS software, the numerical simulations of the three-dimensional flow field in the condensing zone for four kinds of compact spinning systems are obtained. It is shown that the flow field distribution of the condensing zone of roller-type compact spinning is different from that of lattice apron-type compact spinning and the flow field distribution of the condensing zone is significantly related to yarn properties. Comparing with roller-type compact spinning, lattice apron-type compact spinning has lower negative value of the flow velocity in the X-axis direction, a higher value in the Y-axis direction and a higher value in the Z-axis direction. Combined with yarn experiments, it is shown that the flow velocity component in the X-axis direction has an assistant condensing effect and the negative value mainly increases yarn beneficial hairiness. Roller-type compact spinning has a higher negative value and more beneficial hairiness correspondingly than lattice apron-type compact spinning; the flow velocity component in the Y-axis direction has a direct condensing effect, which is of benefit mainly for improving strength and reducing hairiness. Lattice apron-type compact spinning has a higher value and higher strength and less hairiness than roller-type compact spinning; the flow velocity component in the Z-axis direction has an assistant condensing effect, which is mainly of benefit for improving yarn evenness. Lattice apron-type compact spinning has a higher value and better evenness than roller-type compact spinning.