Development of commingling nozzles for hybrid yarn production by CFD simulation

The production of hybrid yarns is a technology which can be applied to manufacture fiber reinforced thermoplastic composites (FRTC) for technical applications. In this case hybrid yarns consist of reinforcing and multifilament thermoplastic fibers. To reduce the flow paths of the high viscous melt during the consolidation of composites a good mixing is essential. A suitable process to generate hybrid yarns is performed by air jets (so-called air commingling). Different nozzle types like air jet texturing and intermingling nozzles are used depending on the yarn count, the mixing behaviour and the mechanical properties of the initial fibers. The technique of Computational Fluid Dynamics (CFD) is useful to analyse the flow field inside the commingling nozzles. In the frame of this paper the procedure during the simulation is described and related to the commingling process. The concept during the development process of nozzles can be carried out through specific parameter studies. In doing so, the commingling process can be optimized. In this way, the distribution of the individual filaments in the FRTC can be systematically improved.