Two-dimensional simulation of air flow in the transfer channel of open-end rotor spinning machines

A two-dimensional computational fluid dynamics model is developed to simulate the flow patterns inside the transportation zone of a rotor spinning machine and analyze their effects on yarn properties. The strength and area of recirculation at the inlet of the transfer channel caused by the geometric variation and rotating opening roller are significantly related to fluid flow, and consequently to rotor spun yarn properties. Any variation of geometric dimensions of the transfer channel or opening roller velocity affects the air flow pattern, which then alters the configuration of fibers flowing inside the channel. A larger inlet at the transfer channel will lead to a decrease in the inlet mean velocity and will strengthen the primary recirculation zone, which is a potential source for fiber curving and buckling. The ratio of the circumferential velocity of opening roller to mean air flowing velocity is identified as a critical parameter to classify differences in flow patterns. If the ratio is a constant, the flow pattern will not explicitly change, but the drag force will increase with the increase in Reynolds number. Additionally, if the ratio is either too high or too low, the flow is not suitable for maintaining high quality in spun yarns due to the occurrence of strong recirculation at the outer cover side or opening roller side.