Simulation And Analysis Of Flow Field Distribution And Fiber Trajectory In Aggregation Region Of Compact Spinning

Since traditional ring spinning has twisting triangular space,the hairiness of the yarn will increase and thus the quality of yarn and its products is seriously affected.For this reason,it is difficult to meet the demands of modern life.The technique of compact spinning is a good solution to the problem of excessive hairiness.Compact spinning is a technique based on traditional ring spinning,in which aggregation region is added.The loose sliver is aggregated in this aggregation region to reduce the twisting triangle,so that the yarn quality will be increased.In this paper,the widely-used four-rollers compact spinning and complete condensing which is independently developed by Jiangnan university are studied.FLUENT is a programming platform to simulate the flow field in the aggregation region,representing the distribution of airflow in the agglomeration region and obtaining numerical characterization of velocity distribution.MATLAB is a programming platform to explore the trajectory of fibers in cluster area to obtain aggregation mechanism of fiber.Then,the mechanism of action of yarn quality under constant negative pressure and variable negative pressure flows is investigated,which helps to improve and optimize the compact spinning system.Firstly,the physical model of four-rollers compact spinning and complete condensing is constructed.FLUENT is used to simulate the flow field in the aggregation region.Secondly,the results of numerical calculation are extracted.Velocity distribution curve is set respectively in the front region,the middle region and the back region of the agglomeration region,then the pressure distribution and velocity distribution of the three representative positions are obtained.The calculated data which is extracted in the agglomeration region is imported to MATLAB to do three-dimensional interpolation.The dynamic model of fiber is established by infinitesimal method.MATLAB is used to edit the dynamic equation to simulate the trajectory of single fiber in the agglomeration region.Finally,the constant negative pressure experiments focus on the trajectory of 18.8Tex cotton yarn under suction negative pressure that is-2800 Pa,-2600 Pa,-2400 Pa and-2200 Pa.The spinning yarn is measured and compared.29.2Tex,14.6Tex,9.2Tex cotton yarn which are spun under suction negative pressure that is-2800 Pa,-2600 Pa,-2400 Pa,and-2200 Pa is used to test.In this paper,the property of yarn is discussed in detail with the distribution of airflow velocity and the trajectory of fibers.The experimental results show that:(1)In terms of flow field distribution,the static pressure distributions of the two are the same,air flows from the both sides of the aggregation region to the inside of the aggregation region.The velocity distributions of the front zone,the middle zone and the back zone in agglomeration areas are roughly same,but the velocity distribution rules of the three corresponding regions are different.The distribution rules of static pressure and velocity are analyzed comprehensively,which shows that complete condensing spinning has better agglomeration impact from the point of view of the action of the airflow.(2)By simulating fiber trajectory,the fiber spun by four-rollers compact spinning at the entrance of aggregation region are compacted and output to the center;The tracking of single fiber is regular,but the displacement of fiber in the intermediate micro-element periodis random.The fibers hold together under the action of airflow force and friction.The fiber spun by complete condensing is distributed orderly,moving straight from the feed point to the center.Single fiber aggregates into small bundles,but few small bundles aggregate into large bundles.Unlike four-rollers compact spinning,the fibers don't get entangled.(3)By doing a series of yarn experiments,it is shown that the effects of pressure of four-rollers compact spinning and complete condensing are similar in the strength of the yarn.Large negative pressure helps to increase the strength of coarse yarn,when suitable negative pressure should be used for spinning medium count yarn and fine count yarn.In terms of yarn evenness,the negative pressure selected for spinning coarse yarn with four-rollers compact spinning should be appropriately large.When spinning fine yarn,the negative pressure should be reduced in complete condensing.Large negative pressure can be used for coarse yarn while appropriate negative pressure can be used for spinning medium count yarn and fine count yarn.