Rotor spinning transfer channel design optimization via computational fluid dynamics

Abstract

The conventional rotor spinning unit generates flow vortices in the transfer channel upstream region which affect the fiber configuration and consequently yarn properties. Geometry and spinning parameters such as transfer channel length, inlet width, rotor outlet pressure, opening roller speed and diameter were found to be key parameters influencing airflow characteristics. To reduce the flow vortices in the upper stream region, modifications of the transfer channel were proposed, and their airflow fields were analyzed using Computational Fluid Dynamics (CFD). Three designs were studied; round transfer channel inlet, a bypass channel for extra air supply and one with both the bypass and the round inlet. Analysis of airflow revealed that the design with both round transfer channel inlet and a bypass proved to be very effective in properly directing the flow and minimizing vortices. The design was also characterized by smoother velocity streamlines and maximum mass flow across the transfer channel. A conventional rotor spinning unit was modified in which a round transfer channel inlet corner and a bypass channel were utilized to conduct the experimental tests. Three sets of yarn samples were produced using the conventional and modified rotor spinning units under different rotor speed conditions. Yarn properties were tested. Properties such as tenacity, CVm%, thin and thick places of the spun yarns produced by the new design improved compared to that of the conventional yarn.

Effect of rotor spinning transfer channel modification on fiber orientation and yarn properties

“…One comes from the bypass channel and the other is from the trash box. In reality, due to the new mass flow coming from the bypass channel, the mass flow from the trash box is smaller than the one existing in conventional units, in any case the overall mass flow is higher in the new developed unit, as proved in (Lin et al, (2018)). This allows higher average air velocity in the fiber transfer channel and decreases air velocity in the trash box.…”

“…The occurrence of high recirculation in the transfer channel inlet area would degrade fiber straightness and consequently decrease yarn properties. (Lin et al, (2018)) further developed a three-dimensional CFD model of the rotor spinning unit to study the vortex inside the transfer channel. They reported that the vortices were decreased either increasing the transfer channel length or the rotor outlet relative pressure.…”

“…The aim of this research is to study the influence of the modified transfer channel proposed by (Lin et al, (2018)) on fiber straightness and yarn properties. Cotton and viscose yarns with different linear densities were spun using the conventional and modified rotor spinning units and their quality properties were statistically analyzed.…”

“…This scenario was initially reported by (Kong & Platfoot, (1996), (1997, 2000). Lately, this particular vortex formation was carefully studied by (Lin et al, (2018)). Nevertheless, as the geometry of the transfer channel affects the airflow path, it consequently changes the path of the fibers from the opening roller pins to the rotor groove.…”

“…The rounded corner radius was 1.5 mm and the bypass inlet area was 5×6 mm. Specific details of the simulation performed, the grid independency test, the Y+ values obtained and a large amount of the simulations performed under different boundary conditions are to be found in (Lin et al, (2018)).…”