Textile fabric's in-plane water permeability determination during wicking

Based on a mathematical formulation of the water flow for different wicking configurations (ascendant-horizontal and descendant), a combined ascendant, horizontal and descendant wicking experimental test was designed to provide detailed measurements of the pertinent wicking performance properties: capillary pressure and in-plane direction permeability. This method was proposed due to capillary flows found in standard vertical wicking tests as well as erroneous assumptions made in other wicking tests. The effective capillary radius was assumed to remain constant as the height of the liquid increases. This assumption would suggest that saturation, capillary pressure, and permeability are also constants. However, experiments show that these properties are only constants in the case of the descendant wicking when liquid front height is varied. The capillary pressure and permeability calculations were made using Darcy’s law and the Lucas-Washburn equation as a function of the saturation level. In the combined wicking test, conducting a horizontal wicking test allows us to calculate the effective capillary radius of a fabric as the saturation rate was found to be constant, which in turn can be used to solve for capillary pressure. That capillary pressure can then be used in a descendant wicking test, where the liquid front flow and the saturation rate remain constant, and Darcy’s law to solve for permeability. A series of experiments was conducted on cotton jersey knitting. The results showed that the ability to wick the water depends on pore size and porosity scales: macro and micropores. The in-plane water permeability was found to be directly related to the saturation rate.