Abstract: "China's textile and apparel industry boasts a complete industrial chain, with a total output value reaching approximately RMB10 trillion in 2023. In the chemical fiber industry, the fiber delivery tube, as a core component of post-processing equipment, has an inlet structure design that significantly impacts the opening and loosening effect of viscose staple fibers. This study employed Cradle CFD software to simulate and analyze the fluid-solid coupling motion of fibers, comparing the performance differences between vertical inlet and 45°, 60° curved inlet structures. Through SolidWorks modeling and calculations using the RNG k-ε turbulence model, it was found that the vertical inlet structure tends to cause fiber aggregation due to insufficient flow velocity uniformity, resulting in poor opening and loosening effect. In contrast, the curved structure utilizes the centrifugal force generated by curvature to create a velocity gradient, effectively promoting fiber dispersion. Specifically, the 60° structure exhibits superior opening and loosening performance due to its greater curvature, although it is necessary to balance the delivering efficiency issues arising from the increased pipeline length. The curved inlet structure significantly enhances fiber processing efficiency through fluid dynamics optimization. Simulation results show that changes in pipeline curvature alter fluid velocity distribution. The centrifugal force generated by the 60° curved structure maintains a continuous velocity difference among fibers, thereby enhancing the opening and loosening effect. The Walton-Braun contact model verifies that this structure effectively reduces fiber plastic deformation, while the Choi dynamic model confirms its suitability for processing highly deformed fibers. Although curved structures extend the transport path, a balance between the opening and loosening effect and production efficiency can be achieved by optimizing the pipeline geometry. This flow field regulation mechanism offers new insights into the design of fiber delivering equipment, demonstrating that the sustained action of local velocity gradients is more conducive to fiber dispersion than a uniform flow field. The research findings offer crucial theoretical support for innovation in textile machinery. The 60° curved inlet structure enhances fiber opening and loosening by intensifying fluid disturbance and centrifugal effects while maintaining high delivering efficiency, offering significant advantages over traditional vertical structures. This achievement not only addresses the technical challenge of staple fiber entanglement, but also reveals the collaborative optimization path between flow field characteristics and mechanical structures. It is recommended that the industry prioritize the adoption of 60° curved design and further investigate the optimal ratio between the radius of curvature and the pipe diameter. This fluid mechanics-based innovative approach will drive the development of textile machinery towards higher efficiency and precision, and serve as a key technological breakthrough for industrial upgrading."

Key words: fiber delivery tube, viscose staple fiber, inlet structure, opening and loosening effect, Cradle CFD

摘要： 为优化输毛管入口结构设计，使用商业软件Cradle CFD对粘胶短纤维在流场中的流固耦合运动过程进行仿真计算，提出并设计了45°和60°弯曲入口结构，分析竖直入口结构对纤维开松效果影响；通过对比分析不同入口结构的仿真结果，研究发现：弯曲入口结构所形成的流体动力学效应会促进纤维的混合、分散和开松，使得弯曲入口结构的纤维开松效果明显优于竖直入口结构，且60°弯曲入口结构优于45°弯曲入口结构。研究结果为纺织行业粘胶短纤维输毛管的设计提供了参考。

关键词: 输毛管, 粘胶短纤维, 入口结构, 开松效果, Cradle CFD