Motion and morphological changes of straight and hooked fibers in high-speed airflow field

In this study, we conducted a simulation to analyze the movement of 28 mm cotton fibers with straight, front-hooked, and rear-hooked morphologies in a rotor spinning unit that included fiber transport channels, rotor slip surfaces, and collection grooves. The results demonstrate that the speed of the straight fibers in the spinning unit follows a pattern of first increasing and then stabilizing. Specifically, within the fiber transport channel, the fiber speed ranged from 22 to 27.4 m·s −1 , with no significant change observed in fiber morphology. Within the rotor itself, the fiber speed range was approximately 27.4 to 115.5 m·s −1 . Furthermore, while both types of hooked fiber exhibited similar morphological changes within the fiber transport channel, at the exit into the slip surface area they exhibited different shapes, specifically when entering the collection groove: for front-hooked fibers, their bent parts would be straightened out completely, whereas it was difficult for rear-hooked fibers’ bent parts to be completely straightened out after entering the collection groove. It was also observed that, within the collection grooves, the straightness of front-hooked fibers was 40%–51% higher than that of rear-hooked fibers. The spinning experiments have revealed that yarn quality is significantly improved when the yarn is spun from raw materials containing a higher proportion of front-hooked fibers. This improvement is evident in terms of breaking strength, elongation at break, evenness, and hair index. The study delves into understanding changes in fiber shape through numerical simulation analysis, providing theoretical guidance for production optimization and design solutions.