Abstract: Rotor spinning utilizes airflow as a driving force to achieve operations such as fiber transport and aggregation. The characteristics of the airflow field during the spinning process directly impact the spinning results. The article employs simulation software to model the movement of airflow within the rotor, investigating the correlation between the airflow field inside the rotor and the quality of yarn. This research provides valuable guidance for enhancing the structure of rotor spinning.
         In order to more accurately identify and analyze the vortex patterns within the complex and dynamic flow field inside the rotor in air-jet spinning, a vortex identification method that combines the Ω vortex determination criteria with image processing is proposed. The method involves analyzing the flow field within the rotor obtained through simulation using FLUENT. This analysis provides insights into the number and area of vortices on the plane of the condensation slot and further explores
        According to the simulation analysis, the results indicate that the distribution of static pressure values on the rotor's surface is uneven, leading to varying pressures at different locations across the rotor. Within the fiber delivery channel, the static pressure gradually increases to -7 kPa as the channel diameter decreases. Notably, there is a substantial static pressure gradient change on the wall surface near the channel outlet.  Inside the rotor, the fastest airflow velocity is observed at the location of the condensation slot, forming a circular ring of high velocity. The middle section of the rotor experiences slower airflow velocities, extending to the entrance of the yarn guide tube. On the side of the rotor closer to the fiber delivery channel, there is a long strip-like region with higher airflow velocity.  Observing the vortices identified using the Ω method, it is evident that this approach has a superior ability to capture vortices within the plane. It not only captures the larger vortices displayed in streamline plots but also effectively captures smaller vortices within the condensation slot that may not be discernible in streamline plots. Additionally, vortices within the condensation slot are primarily concentrated at the outlet of the fiber delivery channel and at the intersection of airflow behind it. This phenomenon arises due to the relatively complex airflow movement in these two positions. As the rotational speed increases, the area of smaller vortices inside the rotor's condensation slot also increases.  The vortex area increases from 14.1 mm² to 18.5 mm², leading to an increase in yarn coefficient of variation from 15.33 to 15.99, resulting in decreased overall yarn uniformity. The increase in rotational speed also leads to an increase in the number of coarse and fine nodes on the yarn, resulting in a decline in yarn quality. When the rotor diameter is increased, the area of vortices within the rotor's condensation slot decreases. The vortex area reduces from 15.6 mm² to 10.7 mm², representing a reduction of 31.4%. The coefficient of variation decreases from 15.53 to 15.02, enhancing yarn uniformity and improving the spinning results. 
        The Ω vortex identification method exhibits excellent capturing capability for vortices on the plane of the condensation slot. After undergoing image processing, this method allows for the quantitative analysis of the vortex patterns within the internal airflow field of the spinning cup. Vortices within the condensation slot are mainly concentrated at the outlet of the fiber delivery channel and at the intersection of airflow behind it. Lowering the spinning cup's rotational speed and increasing its diameter can enhance the quality of the yarn

Key words: rotor spinning；numerical simulation, airflow field, Ω vortex identification method；image processing

摘要： 为了更为准确地识别与分析转杯纺转杯内复杂多变流场中的涡流情况，提出了一种结合Ω漩涡识别方法和图像处理的漩涡识别技术。文章对Fluent仿真得到的转杯流场进行了分析，得到了凝聚槽平面的漩涡数量与面积，并进一步探究了凝聚槽内漩涡分布对纱线质量的影响。结果表明: Ω漩涡识别方法对凝聚槽漩涡有较好的捕捉效果，经过图像处理后可以定量化分析转杯内部气流流场的涡流情况；凝聚槽内漩涡主要分布在输纤通道出口处以及背后气流交汇处；随着转速的提升，转杯凝聚槽内细小漩涡面积增加，不利于纱线聚合；较大直径转杯凝聚槽部位漩涡面积更小，有利于纤维聚合。文章通过图像识别的方式探究转杯内流场的漩涡分布特征，为优化转杯纺结构提供了一定理论支持。

关键词: 转杯纺, 数值模拟；气流场；Ω漩涡识别方法；图像处理