有限元在分析纱线毛羽减除机理上的应用

【作者】 郭会勇；

【导师】 王建坤； 李翠玉；

【作者基本信息】 天津工业大学 ， 纺织工程， 2007， 硕士

【摘要】 纱线的毛羽过多,不仅影响后续工序的顺利进行,而且影响产品质量。一般认为,纱线的毛羽生成于纺纱工序,增长于络筒工序。随着络筒机速度的不断提高,如何控制高速络筒机毛羽的增长幅度,成为人们关注的一个问题。科学技术的发展,使气流,尤其是高速气流,被越来越广泛的应用到纺织生产中。国内外的研究人员通过在细纱机或者是络筒机上安装一个气流喷嘴,利用气流喷嘴内高速气流的作用减少纱线的毛羽。前面的研究工作中,也曾设计了一个减羽喷嘴,通过实验证实,在络筒机上安装减羽喷嘴以后,在一定程度上降低了纱线毛羽的增长幅度。但是,这些研究工作主要基于实验的研究,并没对减羽喷嘴内的高速气流的运动状态进行全面分析,也就无法解释纱线在经过减羽喷嘴时毛羽的减除机理。在本课题中,主要包括三部分:一是减羽喷嘴内气流状态的数值模拟,二是模拟喷嘴的设计和安装,三是模拟喷嘴内纱线运动状态的研究。1.在合理简化的基础上,利用有限元软件ANSYS中的CFD功能,对减羽喷嘴三维简化模型内高速气流进行了数值模拟。模拟的结果显示减羽喷嘴内的气流以涡流状运动。2.为了捕捉喷嘴内纱线的运动状态,根据雷诺数相似的原则,将喷嘴的尺寸放大五倍,并用有机玻璃制作模拟喷嘴,安装在1332络筒机上。3.利用柯达高速摄影技术,在不同纱道直径和气压条件下,捕捉减羽喷嘴内纱线的运动状态,发现纱线在减羽喷嘴中的运动是圆柱螺旋运动,也就是纱线在气流的作用下,形成气圈,边向上运动边旋转,以圆柱螺旋状前进,这一点与理论分析相符。综上所述,纱线毛羽的减少,主要是由于纱线在经过减羽喷嘴时受到涡流的作用。纱线在涡流的作用下形成气圈,并以圆柱螺旋状前进的过程中,利用“假捻—解捻—包缠”原理,纱线的毛羽被包缠进纱体,毛羽减少。更多还原

【Abstract】 If yarn hairiness is too much, it not only affects the following process, but also affects the quality of product. Yarn hairiness generally arises in spinning process and increases in winding process. With the enhancing of winding machine speed, how to control the hairiness increasing extent on the high speed winding machine becomes a problem. Developments in science and technology have made airflow, especially high speed airflow, widely used in textile production.Researchers around the world use the high speed airflow in air-jet to reduce yarn hairiness by installing an air-jet on spinning machine or winding machine. In the anterior research, a reducing hairiness jet is designed and installed on winding machine; it is proved by experiment that yarn hairiness increasing extent is reduced. But the research was mostly based on experiment, and the movement state of high speed airflow in the reducing hairiness jet is not full analyzed, so the hairiness-decreasing principle can’t be explained.There are mainly three parts in this study: first, the digital simulation of the high speed airflow in the reducing nozzle; second, designing and installing of the simulated nozzle; and third, the study on the yarn’s movement in the simulated nozzle.1. Based on reasonable simplification, the digital simulation of the high speed airflow in the three model of the reducing nozzle is done with the ANSYS CFD. The result shows that the airflow in the reducing hairiness jet is vortex.2.Magnifying dimension of the nozzle with five times according to the principle of Reynolds number similar to catch the yarn’s movement in the nozzle, the simulated nozzle which made of organic glass was installed on the 1332 winding machine.3. Use KONDAK high speed photography to catch the yarn’s movement in the reducing hairiness jet in different yarn path diameter and air press. The yarn moves as the shape of column-helical in the reducing hairiness jet, that is to say, under the effect of airflow, the yarn forms air loops, going upwards while rotating in column-helical way, which is in line with the theory analysis.On the whole, it seems that the reduction of yarn hairiness mostly attributes to the function of vortex when the yarn gets through the reducing hairiness jet. Vortex makes the yarn to form air loops, moving in column-helical way. In this process, yarn hairiness is wrapped into yarn body so that yarn hairiness decreases.更多还原