Numerical study of the function of the slotting-tube in air-jet spinning

Abstract

To study the functions of the slotting-tube, the realizable k-ε turbulence model is adopted to simulate the airflow patterns inside three different cases: first nozzle with slotting-tube (case 1), extended first nozzle (case 2), and normal first nozzle (case 3). Simulation results show that owing to the slotting-tube, the strengths of both the reverse flows near the injector upstream wall and the vortex breakdown in downstream of the injector increase. These help to produce more wrapper fibers and form larger twist difference. In addition, negative tangential velocity in the grooves can also help to loosen fiber strands. Therefore, high-quality yarn can be produced in case 1. The flatter pressure distribution also reveals that the existence of slotting-tube increases the flow steadiness. Consequently, the functions of the slotting-tube are demonstrated.

Keywords:

• reverse flow
• vortex breakdown
• injector
• nozzle
• slotting-tube

This work was supported by a grant from the Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP) in China.