Simulation Of Airflow And Optimization Design Of Parameters On Swirl Nozzle

The swirl nozzle spinning is a new technique which is used in reducing hairiness ofconventional ring spinning with airflow. Our group has done a lot of researches in this field.Although the previous swirl nozzles have many advantages of simple structure, convenientusing, and hairiness reducing result is good, but the nozzle structure is still notperfect, causing severe fiber loss and the yarn fineness is not up to the requirement. Thereforethis paper did further improvement for its structure of swirl nozzle. While it also simulatedand analyzed the three-dimensional flow field of the yarn channel on swirl nozzle by thecomputational fluid dynamics software STAR-CCM+, which could understand the airdistribution inside the nozzle, and the influence of nozzle results with different directionand the tangent point of intersection of the airway and the yarn channel, different airwayangles, different airway diameters. Finally, combined with the spinning experiments, the bestparameters of nozzle can be found.Firstly, the paper simulated and analyzed the three-dimensional flow field of the yarnpath in swirl nozzle with different direction and tangent point of intersection of the airwayand the yarn channel by the software STAR-CCM+. Combined with the spinning experimentsderived: when the entrance direction of air flow was Up, the airflow moved to the front nipalong the axial yarn channel in the swirl nozzle. The most of main flow of reducing hairinessdistributed in the airflow and area above the entrance, which could effectively reduce moreforward hairiness of the yarn surface. In the Up group, when airway entrance was in the yarnchannel at2/3, the reducing hairiness result and other yarn performance were the best.However, the entrance direction of air flow was Down, the airflow move to the yarn guidehook along the axial yarn channel in the swirl nozzle. The most of main flow of reducinghairiness distributed in the airflow and area below the entrance, also could reduce hairiness.But its hairiness reducing result and other yarn performance were much less than threenozzles of the Up group. In the Down group, when airway entrance was in the yarn channel at1/3, the reducing hairiness result and other yarn performance were the best. Yet in the Up andDown group, the best one was in Up group, its airway entrance was in the yarn channel at2/3.Secondly, this paper improved the air inlets at different axial angles. In the Up and Downgroup, four nozzles with different axial angle were used (respectively:30°,45°,60°,75°).Simulation and experimental results show following. In the Up group, main flow of reducinghairiness in the swirl nozzle was gradually reduced with nozzle angle increasing. Meanwhile,the gradient distribution of the static pressure along the radial yarn channel was notincreasingly obvious, and the recirculation zone gradually increased in the yarn channel. Sothe number of S3-hairs and other performance of swirl nozzle yarns were depravation. However the swirl nozzle with45°axial angle was the best one. In the Down group,although main flow of reducing hairiness in the swirl nozzle was gradually reduced withnozzle angle increasing, but the flow which could effectively reduce more forward hairinessof the yarn surface was increased. Therefore, even yarn breaking strength and unevenness wasdeteriorated with nozzle angle increasing, the number of S3-hairs was less and less.Eventually, comparison of two nozzle group, using the swirl nozzle with45°axial angle inthe Up group, the yarn performance was the best.Finally, in order to study the influence of airway diameter in swirl nozzle, we used theswirl nozzle with45°axial angle and entrance direction of air flow in Up. STAR-CCM+simulation and spinning experiments found that, swirl nozzle which airway diameter was1.3mm had low axial and radial velocity along the axial yarn channel, the yarn were not windeasily, which could reduce the probability of hairiness wrapped into the yarn body. Theairway diameter of Swirl nozzle at1.5mm had lower tangential velocity, so its tangential forcewas too weak to wrapped hair into the yarn body. The swirl nozzle with airway diameter1.4mm, the gradient distribution of the static pressure along the radial yarn path was obvious,the axial and radial velocity along the yarn channel center line were bigger, the air flowdistribution of whole yarn channel is relatively stable and minimum reflux region. Eventually,when the airway diameter of swirl nozzle is1.4mm, the yarn can achieve the bestperformance and the lowest hairiness.