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Numerical simulation of fiber motion in the nozzle of Murata vortex spinning machine

In this paper, a two‐dimensional model for rationally describing the physical and mechanical characteristics of a flexible fiber is presented. The arbitrary Lagrangian–Eulerian technique is adopted to solve the fluid–structure interaction between the fiber and the airflow in the nozzle of a Murata vortex spinning (MVS) machine. The contact problem arising between the fiber and the nozzle wall is also solved. The motion and deformation of the fiber in the airflow inside the MVS nozzle are successfully simulated. The results show that with the action of the airflow, the fiber shows helical movement with wave shape. During its downstream motion, the fiber contacts the inner wall of the spindle frequently. The trailing end of the fiber whirls within the nozzle chamber with great amplitude. The separation and wrapping motion of the fiber take place and twists are inserted into the fiber strand before the trailing end of the fiber enters the spindle entirely. The intensity of the twists inserted into the yarn can be evaluated by the amplitude and the frequency of the periodical rotation of the trailing end of the fiber.