Numerical study of the three-dimensional preliminary flow field in the ring spinning triangle

The spinning triangle is a critical region in ring spinning. To understand the formation principle of the triangle zone, a dynamic mesh model with SIMPLEC algorithm is employed to study airflow around the rotating front roller-pair. The effects of both the top roller offset and the drafting inclination angle are also discussed. The bubble-type vortex breakdown and vortices around two cylinders are observed. The bubble-type vortices will help the edge fibers to converge to the center. A contour line with special value is defined to describe the spinning triangle. A dynamic triangle zone is also observed with time. As the forward offset of the top roller increases, the velocities in the stream-wise (x- and y-) directions decrease and the maximum values of the skin friction deflect gradually towards the apex of the roller. However, the z-velocity for the 3 mm top roller offset is the largest and results in a good converging for fibers and, consequently, increases the yarn tension. With increasing the inclination angle, the velocities increase while both the defined triangle zones and the maximum values of the friction coefficients decrease, thus speeding up the fibers transportation. The simulation results agree well with the theory analysis and experiments of spinning.