Thesis Details

Thesis Title: The use of computational fluid dynamics to optimize liquor flow profiles in fabric beam dyeing
Thesis Author: William Alex Rapp
Abstract: The most important goal to a dyer is to apply evenly the dyestuffs to the fabric. The basic mechanics of fabric beam dyeing provide a major disadvantage compared to jet dyeing. A higher risk of unlevelness and a lack of understanding of flow through a beam has deterred many dyers from taking advantage of the benefits of fabric beam dyeing. A computational fluid dynamic (CFD) model was used in this work to theoretically test beam dyeing parameters such as fabric permeability, beam density, liquor flow rate, and the position of blank-off collars. The CFD analysis could allow beam dyers to improve quality and/or increase dyeing productivity by providing guidelines to improve side-center levelness and shading from the bottom to the top of the fabric beam. The goal of the analysis was to determine the conditions that produced the lowest percent differences in flow for both the side-center on top of the beam and top-bottom in the core of the fabric beam. Minimizing the percent difference in flow should minimize the differences in dye exhaustion between the areas. Flow losses in the axial direction, or between the layers of fabric, increased the percent differences in flow. Beams with high densities minimized the axial flow. Two fabrics tested both used the lowest percent collar displacements to achieve the lowest percent flow differences, but the fabric with higher axial losses was affected less by the position of the displacement collar. The amount of liquor flow did not affect the percent flow differences, but a correlation between the shade depth at specific positions throughout the beam and its calculated flow showed a relationship where improvements in flow increase the dye exhaustion, but did not increase the dye exhaustion above a critical flow rate.