Study On Weft Yarn’s Instability Behavior During The Start-up Stage Of Weft Insertion

The efficiency of domestic-made air-jet looms have been improved significantly since decades of continuous development. Comparing with oversea advanced techniques, there is still major gaps particular in the reliability and energy consumption. Weft insertion system of air-jet looms is one of key mechanisms, so it is worth studying in depth. During the weft insertion, weft is started with main jet flow from static state. And then, weft yarn flies through the tunnel reeds with assistant airflow and finishes the weft insertion. With the acceleration of the weaving, the opening time of shed becomes very short. It becomes more difficult for weft to fly through the shed and finish weft insertion. Therefore, the stable flight plays a key role. Actually, the tip of weft exits whipping action during the weft insertion, which will affect on the weft insertion’s efficiency. However, there is few study on the whipping action with FSI method.In this paper, weft yarn’s flight during incipient stage of weft insertion is studied with FSI simulation and experimental method. The yarn’s whipping action and corresponding factors are analyzed in depth. These tasks can be obtained as follows:1、FSI simulation. Yarn’s structure model and fluid model of main air flow are modeled. Meantime, these factors affecting on the yarn’s whipping action and the flow characteristics of air flow around whipping yarn are analyzed through simulation results.2、High speed photography experiment. This high speed photography experimental platform is based on type RFJA-10 air-jet loom. The yarn’s flying stage is snapshot by the high speed photography. Then, these experimental snapshots post processed with image processing software. An auxiliary air flow is supplied to adjust yarn’s shape before weft insertion, and its affect on the stability of yarn flight is studied. What’s more, previous simulation results could be verified with experimental results.