Fluid-flow Phenomena in Friction Spinning

An investigation is reported in which dynamic similarity was used to calculate a large–scale water analogue of a friction–spinning torque system that operated with water as the fluid. Reynolds numbers similar to those in an actual machine were used, and the model was geometrically similar. The results showed that leakage flows in the annuli between the rotating perforated cylinders and the stationary inner suction cylinders were very important, as were the relative positions of the suction slots in these inner cylinders. Yarn diameter and rotational speed were also important. With a particular port positioning, it was possible to create cross–flows that could pass behind the yarn from one cylinder to the other. Such cross–flows may be important in carrying portions of fibre from the ingoing roller to the outgoing one and thus help wrap the fibre around the forming yarn end.