Effects of structural parameters on the tangentially injected swirling flow in concentric tubes with different lengths as a model of the vortex spinning nozzle

Abstract

The tangentially injected swirling tube flow has broad applications in various engineering fields. In the textile industry, the vortex spinning technology, which produces short-staple yarns by means of a tangentially injected swirling airflow, is of great prospect in view of its spinning speed and yarn structure. In this paper, the vortex spinning nozzle is abstracted into a model of concentric tubes of different lengths with tangential injectors. A computational fluid dynamics model is presented to study the effects of some structural parameters on the swirling flow generated in this tube system. The particle image velocimetry (PIV) technique is adopted to measure the flow field. Due to the difficulty in duplicating the Mach number, Reynolds numbers are matched between the tube model and prototype in the PIV experiment. Despite the discrepancy between the velocity values provided by the numerical simulation and experiment due to the compressibility effects not being reproduced in the PIV measurement, a comparative analysis concludes that qualitatively matched results on the flow pattern and effects of the structural parameters are obtained by the numerical simulation and PIV measurement.

Experimental study on the formation of core-spun yarn manufactured on a modified vortex spinning system

“…It can be found that the number of fibers in class 3 is the lowest among the three classes, while the number of fibers in class 2 is the highest, that is, more than two times that of class 1. Under the forces generated by the tangential and radial velocity components of the swirling airflow as well as the reverse flow from the spindle, 8,9 the leading ends of some fibers on the outer periphery of the main strand are separated from the main strand and become free, as shown in Figure 8. However, the force generated by the axial velocity component that points downstream 9 tends to suppress their separation, thus generating a small number of fibers in class 1.…”

“…Some researchers followed to investigate the yarn formation principle of vortex spinning via numerical simulation of the airflow characteristics in the nozzle. [7][8][9][10][11] Numerical simulation then became a useful tool by proposing flexible fiber models and modeling the dynamic behavior of the flexible fibers in the flow field inside the nozzle based on which yarn formation principle of vortex spinning was studied. [12][13][14][15][16][17] However, numerical simulation not only simplifies the physical properties of the fibers, but also approximates the boundary conditions of the flow field, and thus presents theoretical results that lack reliability.…”

Numerical investigation on the flow field of a modified vortex spinning system for producing core-spun yarns

“…Due to the high complexity of the flow as a result of the tight space inside the nozzle with an enclosed and complex structure, experimental investigation on the flow characteristics in the nozzle of the vortex spinning system requires sophisticated equipment for flow measurement. 22 As a useful tool for investigating complex flow field encountered in the textile production processes, computational fluid dynamics (CFD) has been adopted by some researchers to analyze the flow field in the nozzle of the vortex spinning system. [22][23][24][25][26][27][28][29] However, in these studies, the influence of the rotating front rollers on the flow field [30][31][32] has not been taken into consideration.…”

“…22 As a useful tool for investigating complex flow field encountered in the textile production processes, computational fluid dynamics (CFD) has been adopted by some researchers to analyze the flow field in the nozzle of the vortex spinning system. [22][23][24][25][26][27][28][29] However, in these studies, the influence of the rotating front rollers on the flow field [30][31][32] has not been taken into consideration. Moreover, there is a lack of publications on the numerical investigation of the flow field of the modified vortex spinning system for producing core-spun yarns.…”

Numerical simulation of flow field in the twisting chamber of Murata vortex spinning based on the hollow spindle with different structures

“…8 In addition, for the sake of investigating the effects of some nozzle and processing parameters on the flow field in the nozzle block of the MVS, a lot of work has been done by Pei and colleagues. [9][10][11] Based on the behavior of the airflow inside the twisting chamber, the influence of airflow on the motion of free end fibers can be further analyzed to clarify the effect of nozzle structure, nozzle pressure, fiber type, spinning speed, and other parameters on the movement law of fibers, and explain the reason for generating thin yarn sections in Murata vortex spinning. 3,[12][13][14][15] In the existing Murata vortex spinning system, the free end fibers lodging on the outer surface of the hollow spindle wrap core fibers to form yarns under the action of swirling airflow.…”