Numerical Simulation of Air Flow in the Nozzle of an Air-Jet Spinning Machine

Abstract

A CFD (computational fluid dynamics) model is developed to simulate the air flow patterns inside the nozzle of an air-jet spinning machine. The design parameters of the nozzle are related to the flow characteristics, so they affect yarn properties. Three parameters are discussed: The effect of nozzle pressure is significant. With increasing nozzle pressure, both the axial and tangential velocity in the nozzle increase, thus increasing the tensile properties of the yarn. However, it is not sensible to increase nozzle pressure to a very high level. The jet orifice angle affects flow characteristics in a complex way. It dramatically affects the axial velocity and the negative pressure at the jet inlet. The selection of a jet orifice angle is a compromise of several factors. Even though the influence of the jet orifice position on the flow structure is insignificant, its design must be optimized. This work demonstrates that CFD can be used to optimize the nozzle design to produce air-jet spun yarns with better properties.