Development of an iterative procedure with a flow solver for optimizing the yarn speed in a main nozzle of an air jet loom

In this research, a fluid–structure interaction (FSI) framework was established to estimate the velocity of a yarn as it is propelled by the main nozzle. To allow the methodology to be used in an optimization context, the computational time was limited as much as possible. The methodology was first validated on polymer coated yarns to avoid any influence of yarn hairiness. Results from the calculations were compared to experiments and adequate agreement was found without tuning. Subsequently, an extension to hairy yarns was made by representing the hairiness as a wall roughness. The roughness height was determined by matching the simulated to the experimental velocity for a single case. The approach was validated by applying the obtained roughness height to different setups and comparing the simulations to the corresponding experiments. Taking into account some limitations, the methodology can be applied for optimization purposes using either smooth or hairy yarns.