Computational Two-Phase Air/Fiber Flow Within Transfer Channels of Rotor Spinning Machines

The pneumatic conveyance of fibers within confined channels is particularly relevant to textile engineering, with applications such as transporting individual fibers within rotor spinning machines. The channels of converging shape within these machines are designed to help straighten the orientation of the fibers that have escaped from the opening roller. This allows a satisfactory configuration of fibers to be presented to the spinning rotor surface, which in turn improves yarn and subsequent fabric properties. In this study, a new air/fiber two-phase model is developed to simulate fiber movement within confined channels. The computation is based on the results from single-phase air flow simulations in a one-way coupling Lagrangian strategy for predicting fiber trajectories. Initial fiber position and the underlying air flow pattern are demonstrated to be critical to the final fiber configuration at the exit of the channel. A streamwise straight fiber tends to generate a leading hook, while a cross fiber is subject to bending. The aerodynamic forces very nearly retain the fiber configuration adopted at the channel inlet without significant improvement of fiber straightness, since hooks are simultaneously generated and eliminated during transport. Fiber opening and fiber detachment from the opening roller are identified as the two critical factors in obtaining straight fibers at the channel inlet and their transport to the spinning zone.