Numerical simulation of flow field in the twisting chamber of Murata vortex spinning based on the hollow spindle with different structures

The novel hollow spindle with spiral guide grooves is introduced into the manufacture of Murata vortex spun yarn for the sake of enhancing the vortex yarn’s strength. By means of numerical simulation, the airflow characteristics in the conventional twisting chamber and novel twisting chamber of Murata vortex spinning are obtained and compared in order to explain yarn formation for adoption of the novel hollow spindle. The airflow distribution near the spiral guide grooves is analyzed, and the influence of airflow changes caused by the groove structure on the movement of the free end fibers and the yarn strength is analyzed. The results show that the spiral guide grooves will influence the pressure and velocity distribution in the twisting chamber, especially near the areas of the guide grooves. The guide grooves can guide the swirling airflow moving down the conical cavity of the twisting chamber, resulting in increases of the tangential, axial, and radial velocities of airflow in the conical cavity. And it is expected to produce fiber migration in the yarn cross-section and the self-twist effect of wrapped fibers. These phenomena will strengthen the wrapping and twisting effect of the free end fibers and inter-fiber cohesive force of vortex spun yarn in the process of yarn formation, and finally improve the strength of vortex spun yarn due to adopting the novel hollow spindle.