A study of the twisted strength of the whirled airflow in Murata vortex spinning

In Murata vortex spinning, the high-speed whirled airflow twists the open-end trailing fibers converged at the inlet of the hollow spindle into a yarn. The twisted strength acting on the vortex spun yarn by the whirled airflow was investigated by an analytical model based on simulating the flow field inside the nozzle block. The results showed that the twisted strength acting on the vortex spun yarn by the vortex could be regarded as the following functions: (1) the number of jet orifices, the jet angle, the inner diameter of the jet orifice and the nozzle block; (2) the distance from the inlet of the nozzle block to the inlet of the hollow spindle; (3) the projecting height of open-trail-end fibers twined over the top exterior of the hollow spindle; (4) the vortex spun yarn diameter; and (5) the velocity at exit of the jet orifice (i.e. corresponding to nozzle pressure). Increasing the velocity at exit of the jet orifice increased the strength twisted by the whirled airflow. The strength twisted by the whirled airflow increased with decreasing inlet diameter of the nozzle block, and was enhanced with increasing outer diameter of the hollow spindle. The strength twisted by the whirled airflow was weaker when the distance from the inlet of the nozzle block to the inlet of the hollow spindle was bigger. The numerical results validated the effectiveness of the analytical model.