The yarn suction gun (YSG) is used to draw the running yarn in the initial phase and when changing the bobbin in a continuous yarn production and is usually operated with compressed air. With a ...typical overall efficiency of compressed air generation, treatment and delivery, the electrical power requirement increases to over 75 kW just to operate a single YSG. Such high electrical power consumption must be addressed. One of the most effective ways to reduce the cost of compressed air generation and treatment is to replace the existing technology with one that is less energy intensive. Based on centrifugal blowers used in vacuum cleaners, a prototype was built and connected to various mixing chambers. Simulations and measurements were performed to evaluate the tension force acting on the yarn. Research on the use of vacuum for yarn suction is presented. It is estimated that after optimizing the suction by using vacuum, only 20 kW of electrical power will be required for one YSG, halving the cost of the current approach using compressed air generation.
HYPOTHESIS 1: To significantly improve the efficiency of yarn suction gun (YSG), the existing technology must be significantly modified or reinvented.
HYPOTHESIS 2: The application of convergent-divergent nozzles enables supersonic airflow velocities in rough vacuum.
HYPOTHESIS 3: A modified YSG can be operated with a rough vacuum instead of compressed air to achieve significantly higher overall efficiency and reduce power input and carbon footprint.
The use of vacuum for yarn suction is presented.
The application of convergent-divergent nozzles enables supersonic airflow velocities in rough vacuum.
The results of this preliminary study show tremendous potential for energy savings and carbon dioxide emission reductions from an alternative approach to yarn suction.
We consider a method aimed at screening contaminants with the help of local exhaust ventilation whose important element is a local suction gun. We investigate the influence of the ratio of the ...geometric sizes of the suction gun and the circular hole and the ratio of the flow rates of intake and suction air on both the distance of suction entrapment and reduction of the dust flows in local closed-type suction guns. We also consider local suction guns in unbounded, semibounded, and bounded spaces.
The yarn suction gun is a kind of fluid machinery using compressed air as power. Airflow geometry in the gun has a significant influence on the airflow distribution, which decides the yarn suction ...performance. To clarify the effect of the nozzle structure on the yarn suction performance, we designed 16 nozzles, determined yarn suction force F, mass flow rate of compressed air G and analyzed yarn suction efficiency η, which is defined as the ratio of F to G. The rational geometrical parameters are obtained as follows: the number of jet orifices N = 3, jet orifice diameter d = 1.6 mm, jet orifice angle Φ = 75° and passage diverging angle of the nozzle θ = 60°. A smaller N reduces the conflict between jet streams and then increases η. Decreasing d contributes to greater η but smaller F. In the range of Φ ≤ 75, increasing Φ causes both F and η to increase. An appropriate θ promotes the yarn suction performance by helping the injected air to go forward smoothly and reducing backflow. It is more rational to use η to evaluate the yarn suction performance.
Yarn Motion in an Air Suction Gun LI, Yonggui; IEMOTO, Yoshiyuki; TANOUE, Shuichi
Journal of Textile Engineering,
2011, Letnik:
57, Številka:
2
Journal Article
Odprti dostop
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 vyc. 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 vac 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.
The yarn suction efficiency of an air suction gun is closely related to the airflow patterns, which are strongly affected by the geometry of the gun. To obtain basic data for the optimum design of a ...gun, we investigated the airflow patterns in the gun with different geometrical parameters by numerical simulation and discussed the relation between the flow patterns and yarn suction force Fm. Compressed-air inflow angle plays an important role in generating a helical flow by controlling circumferential velocity component vc in a yarn propulsion tube. This helical airflow greatly promotes yarn suction capacity. Fm has a closer relationship to the distribution of air velocity than air pressure, and strongly depends on vc. The airflow patterns are weakly dependent on a passage diverging angle of nozzle and a converging angle of de Laval tube. A reduction in throat diameter of de Laval tube causes a rapid extension of the supersonic flow area near the throat accompanied by increasing axial velocity component in the de Laval tube. However, it leads to decreases in vc in the yarn propulsion tube and air velocity in the yarn inhalation tube, which hinders the promotion of Fm.
We investigated numerically flow patterns in the air suction gun and dependence of the flow pattern on the supplied air pressure in order to clarify the working mechanism of an air suction gun. The ...compressed air issued from compressed-air inflow tubes into a yarn passage accelerates with sucked ambient air owing to negative pressure generated by the compressed air, and attains a critical speed near the throat of the de Laval tube and a supersonic speed in the divergent part of the de Laval tube. The supersonic flow generates a normal shock wave and changes into a subsonic flow. Then, the air is discharged into the atmosphere. Since this compressed air has a circumferential component, it forms a helical flow along the wall of the yarn propulsion tube composed of the de Laval tube and the straight tube. Velocity and density of the helical airflow near the wall are larger than those near the centerline. The suction efficiency is promoted greatly owing to this high focusing ability (bias of high speed and density flow toward the vicinity of the wall) and a large yarn length in the helical airflow. Increased supplied air pressure brings about increases in both air density and supersonic flow region, which promotes the yarn suction force.
Yarn Posture in an Air Suction Gun Li, Yonggui; Iemoto, Yoshiyuki; Tanoue, Shuichi ...
Journal of Textile Engineering,
2010, Letnik:
56, Številka:
6
Journal Article
Odprti dostop
The geometrical effects of an air suction gun on yarn motion were clarified by measuring postures of a running yarn with a still camera in order to promote the suction performance by controlling the ...yarn motion appropriately. The relation between the yarn posture and yarn suction force was also discussed. The yarn posture is a helix. This helical motion greatly improves the suction efficiency of the air suction gun owing to high concentration of air drag on the yarn. Helix diameter of yarn posture dy and helix pitch of yarn posture py decrease with an increase in the compressed-air inflow angle and a decrease in the throat diameter of de Laval tube, and are almost independent of the passage diverging angle of nozzle and the converging angle of de Laval tube. Unfavorable values of the geometrical parameters cause large fluctuations in yarn postures, i.e. violent yarn motion. A stable yarn posture with appropriately small dy decreases the friction between the yarn and the wall of tube, and an appropriately small py increases the contact area between the yarn and the air. Hence the yarn suction force is promoted.
We experimentally discussed the effects of airflow geometries in an air suction gun on the suction characteristics of running yarn. Geometry parameters focused on were 1) compressed-air inflow angle ...of nozzle, 2) diverging angle of nozzle, 3) throat diameter of de Laval tube, 4) converging angle of de Laval tube and 5) yarn propulsion tube length. As a result, effects of the geometry parameters on the yarn suction force, the mass flow rate of compressed-air and the yarn suction efficiency, which is defined as the yarn suction force divided by the mass flow rate of compressed-air, were made clear and the optimum geometry of an air suction gun was obtained on the basis of the energy efficiency. In addition, the yarn suction force showed two types of time dependency because of different yarn motion on some experimental conditions.
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