Numerical study of flows for slub yarn transmission in an air jet

This paper focused on the investigation of the slub yarn parameters and the relationships of the aerodynamic friction along the surface of the slub yarn. The calculation of the frictional drag force was analyzed for spun yarns, which proves it has an irregular surface due to the irregularity of the yarn diameter along its length. In the case of slub yarns, the main descriptive parameters such as slub length, slub distance, slub multiplier, and base yarn count, will affect the air drag coefficient. A methodology for the calculation of the coefficient of air drag along the yarn in an airstream was developed for both regular and slub yarns under different conditions. The air frictional drag coefficients of yarn samples were calculated accordingly. Finally, empirical equations were developed. Calculations of the air friction drag coefficient of slub yarn were determined. The experimental results agreed well with the model predictions and showed that the present model had a high prediction accuracy.