Three-dimensional fluid-structure interaction simulations of a yarn subjected to the main nozzle flow of an air-jet weaving loom using a Chimera technique

In air-jet weaving looms, the main nozzle pulls the yarn from the prewinder by means of a high velocity air flow. The flexible yarn is excited by the flow and exhibits high amplitude oscillations. The motion of the yarn is important for the reliability and the attainable speed of the insertion. Fluid-structure interaction simulations calculate the interaction between the air flow and the yarn motion and could provide additional insight into yarn behavior. However, the use of an arbitrary Lagrangian–Eulerian approach for the deforming fluid domain around a flexible yarn typically results in severe mesh degradation, vastly reducing the accuracy of the calculations or limiting the physical time that can be simulated. In this research, the feasibility of using a Chimera technique to simulate the motion of a yarn interacting with the air flow from a main nozzle was investigated. This methodology combines a fixed background grid with a moving component grid deforming along with the yarn. The component grid is, however, not constrained by the boundaries of the flow domain allowing for large deformations with limited mesh degradation. Two separate cases were investigated. In the first case, the yarn was considered to be clamped at the main nozzle inlet. For the second case, the yarn was allowed to move axially as the main nozzle pulled it from a drum storage system.