Yarn Motion in an Air Suction Gun

Abstract

In order to clarify the working mechanism of an air suction gun, yarn motion in the air suction gun was captured with a high-speed video camera, then characteristics of the yarn motion in the air suction gun and the geometrical effects on the yarn motion were investigated. A yarn moves forward with a high-speed rotation in a yarn propulsion tube, and performs a helical motion more regularly in a de Laval tube than in a straight tube. The motion path is different from the yarn posture. The yarn motion is unsteady and considerably affected by the friction from the tube wall, which causes a large reduction in the yarn circumferential velocity component v yc. The changes in the geometrical parameters mainly produce changes in vyc with a negligible effect on the yarn axial velocity component. vyc increases with an increase in the compressed-air inflow angle and with a decrease in the throat diameter of de Laval tube. An increase in the convergence angle of de Laval tube causes vyc to increase in the de Laval tube. Yarn motion is almost independent of the passage divergence angle of nozzle. It is mainly determined by the circumferential component of air velocity v ac and bears less relationship to the axial one. Yarn suction force Fm is associated with various effects, and depends on vyc in particular. For achieving a high Fm, the swirl intensity of helical airflow, namely vac, needs to be controlled at an appropriate level because an increment of vac increases both air drag on the yarn and friction between the yarn and the tube wall.

Design of the nozzle of a yarn suction gun for fully drawn yarn

“…16,17 However, the effect of nozzle structure, especially the number of jet orifices and jet orifice diameter, still remains unclear.…”

“…In order to provide a technological support for designing a YSG with high performance such as strong suction of yarn and low consumption of compressed air, Iemoto et al 13 and Li et al [14][15][16][17] have conducted a systematical study on the effect of four geometrical parameters of a YSG for polyester fully drawn yarn (FDY) , which is the most representative, on the yarn suction performance, 13 flow field 14,15 and yarn motion. 16,17 However, the effect of nozzle structure, especially the number of jet orifices and jet orifice diameter, still remains unclear.…”

Laval Tube Design of Yarn Suction Gun for Fully Drawn Yarn

“…In order to determine the suitable geometry of the YSG from the viewpoint of energy efficiency, the performance of the YSG was investigated by yarn suction efficiency (η=F/G), defined as the ratio between the yarn suction force (F) to the mass flow rate of compressed air (G). This evaluation method has been used in the literatures [13][14][15][16][17][18]. …”

“…In order to provide the technological support for structural design of the YSG with high performances such as strong suction of yarn and low consumption of compressed air, the systematical studies on the effects of four geometrical parameters of YSG for polyester FDY on the yarn suction performance, flow field and yarn motion have been reported by researchers [13][14][15][16][17][18]. The nozzle of the YSG was also improved by Li and coworkers [18].…”

Numerical Simulation Analysis of Influence of Jet Orifice Structure on Fluid Field in Yarn Suction Gun for Fully Drawn Yarn

“…systematically studied the influence of the main structural parameters of FDY yarn suction gun on yarn suction efficiency [6], flow field [7,8] and the yarn movement [9,10]. Li etc.…”