Numerical simulation analysis of the influence of ultra-fine glass fiber production process on product homogeneity

Glass fiber felt is produced by flame blowing process, in which primary glass filament splits into glass fiber through the gas jet into the diffusion duct. In the diffusion duct, the velocity difference at axial direction creates a fiber recirculating zone at some position downstream in the duct while affecting the homogeneity of the product. In order to understand the impact of diffusion duct design to the felt forming, numerical simulations with experiment-based boundary conditions were performed to investigate the movement of fiber suspension flow. In the numerical analysis, the fiber slender-body theory is introduced. A visualization method is developed to characterize the uniformity of glass fiber, through charge coupled device camera imaging demonstrating the intensity of glass fiber in the surface of the product. The proposed methodology enabled new design of the diffusion duct, which eliminated the recirculating zone in the duct, resulting in more uniform products.

SIMPLE MODELS FOR WALL EFFECT IN FIBER SUSPENSION FLOWS

Jeffery's equation describes the dynamics of a non-inertial ellipsoidal particle immersed in a Stokes liquid and is used in various models of fiber suspension flow. However, it is not valid in close neighbourhood of a rigid wall. Geometrically impossible orientation states with the fiber penetrating the wall can result from this model. This paper proposes a modification of Jeffery's equation in close proximity to a wall so that the geometrical constraints are obeyed by the solution. A class of models differing in the distribution between the translational and rotational part of the response to the contact is derived. The model is upscaled to a Fokker–Planck equation. Another microscale model is proposed where recoiling from the wall upon the collision is permitted. Numerical examples illustrate the dynamics captured by the models.