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The application of the air jet loom is widespread in the textile industry because ofits high productivity, convenient controllability, high filling insertion rate, low noise andlow vibration levels. Air stream in confusor guides can be classified into two types. A weftyarn ejected with high speed air flow is given the drag force caused by friction...
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... High filling insertion rates, low noise and vibration levels, reliability and low maintenance costs, low spare parts requirements, low space requirements, relatively simple operation, reduced hazards due to few moving components, and a low initial outlay are its outstanding qualities (Adanur 2020). This feature makes it the most selective loom among others for the production of light to medium weight fabric, and its application in the textile industry is widespread (Szabó, Patkó, and Oroszlány 2010). On the other side, it has some limitations; for instance, loss of weft yarn twist during insertion and its high power consumption are the most determinant drawbacks of this loom (Göktepe and Textile 2008;Ketema, Ayele, and Million 2023). ...
... Where: ρ -air density; [kgm− 3 ], C f -skin friction coefficient, X -is the direction of weft yarn movement, D -yarn diameter [m], L -Length of the weft along the reed width [m], V -weft yarn velocity [ms− 1 ], U -air velocity [ms− 1 ], and F f -friction force (Szabó, Patkó, and Oroszlány 2010). The yarn is pulled by the air at the tip rather than pushed from behind through the insertion to minimize buckling (Adanur 2020). ...
Production of high-quality woven fabric with uniform fabric properties is an essential requirement for manufacturers. But in air-jet weaving, some quality parameters of the fabric are affected by twist loss of weft yarn during weft insertion. The aim of this work is to show the effect of polyester/cotton (PC) blend ratio, loom speed, and air pressure on weft yarn twist loss and tensile properties of the fabrics produced by air-jet weaving machines. Box-Behnken design has been used to design and analyze the experiment. 27 fabric samples were on an air-jet loom with a combination of four factors each at three levels (loom speed (A) 300rpm, 425rpm, and 550rpm), left side relay nozzle pressure (LSRNP) (B) (2.5 bar,3.25 bar, and 4 bar), Right side relay nozzle pressure (RSRNP)(C) (3 bar, 4.75 bar, and 6.5 bar), cotton/polyester blend (D) 100%/0%, 75%/25%, and 50%/50%,). The results of the experiment revealed that PC blend ratio, loom speed, and air pressure affect the twist level and the strength of the yarn significantly. It is found that relay nozzle air pressure is directly proportional to the twist losses and weft yarn strength loss. But the PC blend ratio has a more significant impact on weft yarn twist loss and mechanical properties of the yarn.
... The tip of the weft is pulled by the drag force crated between the yarn surface and the blowing air. The drag force depends on air density, yarn surface characteristics, velocity difference between air and the weft yarn, yarn diameter, and weft yarn length (Szabó, Patkó, and Oroszlány 2010;;;Belforte et al. 2011). ...
Weaving industries that use air jet loom are always emphasized to increase production and keep up the quality of woven fabric. But due to faulty mill practices or negligence, fabric mechanical properties of the fabric made on air jet loom are impaired. Improving the fabric quality can be achieved by improving work practices and optimization. The aim of this research is to optimize the air pressure and loom speed to produce a fabric with optimum mechanical properties and twist loss of weft yarn after weaving. To perform the experiment, three independent variables (loom speed, left-side relay nozzle pressure, and right-side relay nozzle pressure) was taken. With the combination of the three independent variables at five levels each, nineteen fabric samples were produced and each tensile and tear strength of the fabric in the weft direction were tested. Central composite design (CCD) was used to design the experiment, analyze the results of the experiment, and optimize the process. The results of the experiment show that variation in loom speed and air pressure affects twist of the weft yarn and mechanical properties of the fabric significantly and loom speed had a most significant effect on yarn twist loss, fabric tensile, and tear strength.
... Nosraty et al. 5 used the model from Adanur and Mohamed 3 as a basis for their model to analyse the influence of yarn count and air supply pressure on weft yarn tension. Szabó et al. 6 established a similar methodology for confusor guide systems. They described the air flow in the confusor guides by an empirical model. ...
In air-jet weaving looms, the main nozzle pulls the yarn from the prewinder by means of a high velocity air flow. The flexible yarn is excited by the flow and exhibits high amplitude oscillations. The motion of the yarn is important for the reliability and the attainable speed of the insertion. Fluid-structure interaction simulations calculate the interaction between the air flow and the yarn motion and could provide additional insight into yarn behavior. However, the use of an arbitrary Lagrangian–Eulerian approach for the deforming fluid domain around a flexible yarn typically results in severe mesh degradation, vastly reducing the accuracy of the calculations or limiting the physical time that can be simulated. In this research, the feasibility of using a Chimera technique to simulate the motion of a yarn interacting with the air flow from a main nozzle was investigated. This methodology combines a fixed background grid with a moving component grid deforming along with the yarn. The component grid is, however, not constrained by the boundaries of the flow domain allowing for large deformations with limited mesh degradation. Two separate cases were investigated. In the first case, the yarn was considered to be clamped at the main nozzle inlet. For the second case, the yarn was allowed to move axially as the main nozzle pulled it from a drum storage system.
... In principle, the movement of the weft thread through the reed channel is split into the acceleration phase and the braking phase. Szabó et al. (2010) divided the acceleration phase further into intense and weak acceleration sections. This division is attributed to the different contributions of the components in different times. ...
During the weft insertion in air-jet weaving, a yarn brake plays an important role in reducing the tension when braking the weft thread. An inappropriate braking process can cause backward movements of weft thread, fabric defects and also larger material consumption. For these purposes, this paper proposes a model predictive control system. Regarding external forces from nozzles and weft internal dynamics, a weft insertion process model is developed. Particularly, as the essential accelerating force, the aerodynamic force is dependent on the dynamics of airflow in time and space domain. The model is then validated in order to determine the model parameters. Considering state observation and computational efforts, a control-oriented model is derived based on the analysis of system dynamics. A model predictive controller takes advantage of this reduced model to predict the system behavior in the future. Furthermore, the constraints on the velocity of weft tip are considered explicitly in the optimization problem such that backward movements of the weft thread are avoided. Finally, the simulated position and velocity behaviors of weft thread are presented. The controlled weft is able to arrive at the desired position without constraints on velocity violated.
... They found that by decreasing the mass of the we yarn and increasing its hairiness decreased the insertion time. Celik et al. [130], Nosraty et al. [131], Patkó [132] and Szabó et al. [133] derived the equation of yarn motion in air jet weaving machines and solved it numerically to calculate yarn's position and velocity [130,133] or yarn tension [131]. ...
... They found that by decreasing the mass of the we yarn and increasing its hairiness decreased the insertion time. Celik et al. [130], Nosraty et al. [131], Patkó [132] and Szabó et al. [133] derived the equation of yarn motion in air jet weaving machines and solved it numerically to calculate yarn's position and velocity [130,133] or yarn tension [131]. ...
Air flow is employed in many textile processes to transport or to excite yarns to move in specific directions. Air flows cannot be controlled completely, which leads to some deviations or unexpected behaviour of the guided objects like a yarn. In this research, the interaction between a yarn and the surrounding air flow is studied in two applications: yarn splicing and yarn weaving. Both applications involve compressible flow and it is found that the compressibility effects on the turbulence have to be taken into account. In the first application, yarn splicing is studied based on air flow simulations. The CFD results are linked to experiments and the best flow characteristics are determined. The second application focuses on the main nozzle, which is an essential part of an air jet weaving machine. The geometry of the main nozzle is optimized to give the highest axial aerodynamic force, thus the highest weft yarn speed. The motion of a weft yarn inside a main nozzle is modelled by coupling a 2D axisymmetric fluid model and 3D structure one. The effects of the yarn motion on the air flow are added by a source term to avoid the problems of employing a dynamic mesh which is proven to be complex with a flexible object like a yarn.
... Szabo et al. conducted an experiment to measure the coefficient of skin friction in which a U-tube manometer connected to a Prandtl tube placed at the end of a glass tube was used to determine the flow speed. 9 In 2010, Tesar implemented a non-contact measurement method for the speed of weft yarn by employing viscous dragging in the surrounding air by the moving weft yarn. 10 Using opto-electronic sensors, Fadi J described in his series of papers two devices with different numbers of sensors to measure the velocity of weft yarn. ...
Air-jet weaving is a weaving technique with high production rate. However, efficiency decreases if instabilities in the motion of the weft yarn leader occur causing weft insertion failure. A 2D geometrical model was developed for the main nozzle of the air-jet loom and a mathematical model employing the fluid–structure interaction (FSI) technique was used to simulate the air-flow and whipping action of the leader in the air flow at the exit of the main nozzle. With numerical results, the resultant force normal to the yarn determined by the yarn shape and the air-flow field has a significant influence on this whipping action. Starting with an initial gravity-induced drooping leader, a large normal force exerted by the air flow subsequently leads to a strong whipping action. To verify the validity of the numerical analysis, an experimental apparatus with a high-speed camera attached was constructed to observe the leader trajectory under different air supply conditions. The experimental results show that during weft insertion the motion is more stable with an initially straight leader than one initially drooping.
... However, since the weft speed is ignored in this study, the shear stress is also ignored. because our studies were made for motionless weft [5]. ...
... The driving force for weft yarn moving in air jet is shown in Fig.3 by the friction between the air and the chamber surfaces. 2 2 u X D c F f fr (5) The space between the air stream and the thread is proportional to the square of the relative velocity and the Reynolds number and varies depending on the surface friction coefficient of the driving force. Because deviation from the center of the flow chamber slows down the moving speed of the weft, the turbulence of the air flow will be reduced. ...
The air jet loom is widely applied in the textile industry due to its high productivity, convenient controllability, high filling insertion rate, low noise and low vibration levels. High-Speed air jet weaves the weft yarn, and transports it through the weft passage. In the present study, a computational fluid dynamics method is applied to solve the incompressible Navier–Stokes equations with one-equation Spalart-Allmaras turbulence model. Which is used to solve the flow filed in a weft passage. The aim of this analysis is to determine the distribution of the flow velocity along the weft passage. Results revealed the strong relationship between air jet velocity and forces on the weft.).
Air-jet weaving is one of the most efficient manufacturing processes for producing textile fabrics. During weft insertion, a yarn brake influences the quality of textile fabrics significantly. This brake is set up manually by a machine operator and the duration of the set-up process depends essentially on his experience. Furthermore, an inappropriate braking process might induce high tension in the weft thread which could cause backward movements of the thread as well as a defect in the fabric. For this reason, a braking system is developed which consists of a camera-based sensor and a continuously adjustable brake. The camera-based sensor enables the estimation of the weft velocity which is then controlled by a Model-based Predictive Controller (MPC). In this contribution, a weft insertion model is derived and validated experimentally. After that, this model is reduced in order to ensure real-time capability for its application in a Kalman filter as well as in the MPC. Finally, an MPC based on piecewise linearisation is proposed and implemented on an air-jet weaving machine. The presented experimental results show that yarn braking system compensates the changing behaviour of weft threads in different machine cycles and brakes the weft thread appropriately without a backward movement.
