In many textile machines, a yarn needs to be unwound from a cylindrical package to be processed. During this unwinding the yarn is subjected to several forces, including a tractional force on one end and resistance forces at the other end, but also aerodynamic and centrifugal forces due to the swirling motion of the yarn through the air and contact forces due to contact with rigid surfaces. The interplay between the forces is important to predict the behaviour of the unwinding, but it is not fully understood.
Figure 1: Unwinding of a yarn from a cylindrical package, creating so-called balloon formation.
In this thesis, you will investigate the so-called balloon formation when unwinding a yarn from a cylindrical package. This will be investigated by performing fluid-structure interaction (FSI) simulations in which you will combine a computational fluid dynamics (CFD) model with a beam finite element model (FEM) for the yarn. This model will capture the dynamic swirling motion of the yarn through the air. Subsequently, you will perform a sensitivity study to identify the dominant parameters, using dimensional analysis and/or numerical experimentation. Finally, based on data from these FSI simulations, you will make a fast and simplified model which relates the extraction force to the dominant parameters. The extraction force will thus be written as a function of (or a set of functions of) the yarn mass, unwinding speed, distance to the unwinding point and possibly other parameters, without the need for further CFD/FSI simulations.
You will learn to