Dynamics of the Ramie Yarn Hair in the Nozzle of the JetWind Process and Effects of Some Nozzle Parameters

The technique of reducing yarn hairiness using an air-jet nozzle on the winder (JetWind) is a combination of the ring and air-jet spinning technologies. The dynamics of the hair inside the nozzle plays an important role in the JetWind process. In this study, a dynamical model for the coupling between a protruding surface hair on the ramie yarn and the airflow in the JetWind process is developed. Based on the model, numerical simulation of the dynamics of the hair in the nozzle is performed and the principle of reducing yarn hairiness is theoretically shown. The simulation result is validated by the experimentally captured motional configurations of the hair in the nozzle using high-speed photography technique. The effects of two nozzle parameters—the injector angle and yarn passage diameter on the dynamics of the hair and in turn, yarn hairiness are investigated by both numerical simulation and experiments.