Simulation of Airflow in Nozzle-ring Spinning using Computational Fluid Dynamics: Study on Reduction in Yarn Hairiness and the Role of Air Drag Forces and Angle of Impact of Air Current

In this paper we report on computational fluid dynamics (CFD) simulation of airflow inside the nozzles used in Nozzle-Ring spinning. Using the CFD, air velocities at different locations of the nozzle were obtained and then drag forces acting on hair and yarn were computed. Z-twisted carded cotton yarns were produced at ring spinning machine with and without placing nozzle. Three nozzles were used, each having air inlets at different axial angle. Using the results of simulation, the role of air drag forces and angle of impact of air current on reduction in yarn hairiness could be explained. Nozzle-Ring yarns had a lower number of S3-hairs than the regular ring yarn. The drag forces played a dominant role in reducing the hairs. The angle of air inlets controlled the impact angle of air on the hair. At very high impact angle, curving of protruding hair was bound to occur during its folding, signifying the difficulty in wrapping the hair over the yarn and, hence, a lower reduction in hairiness.