A New Method for Pore Structure Analysis Using Air Flow

Abstract

A new method of analyzing the absolute sizes and distribution of flow channels in porous textiles open to air flow is introduced. The state of the air flow through a textile over a range of pressure drop is ascribed to additive effects of linear or nonlinear flow in separate flow channels. Changes in flow status in given size channels with pressure produce identifiable inflection or transition points that are assumed to occur as the air attains a universal critical shear stress for air in any channel. The inflection points are resolved using a modified permeometer. A force description of the flow relationship in terms of pressure drop, shear stress, and the channel diameter allows all absolute structure information to be evaluated. Relative and absolute sizes of individual flow channels are determined from the transition differential pressure as sociated with the flow transformation in individual channels. The exponent of the power function describing the flow over a given pressure drop region is related to the open areas experiencing laminar and turbulent flow and is used to determine relative areas having a given size channel.