Effect of Fiber Orientation on Air Permeability of Fibrous Layers

• Published in: Research Journal of Textile and Apparel 2009-05, Vol.13 (2), p.9-18
• Main Authors: Kornoohin, I.P., Kornoohina, T.A., Mironov, S.A.
• Format: Article
• Language: English
• ISSN: 1560-6074; 2515-8090
• DOI: 10.1108/RJTA-13-02-2009-B002

The experimental setup for studying fibre orientation effects on air permeability of fibrous layers is described. The orientation parameter is obtained through small-angle scattering by laser radiation. Experimental dependence of pressure drop on air velocity follows Darcy's law. Permeability factors depend on orientation parameters and effective density of porous layers. It is demonstrated that for a fibrous layer porosity of ε > 0.9, the streams around individual fibres may be considered independent. In such a case, the resulting force acting on the entire layer can be defined by force summation over individual fibre length. Resistance force acting on the unit segment of a fibre inclined at an angle to the flow direction is specified by the formula involving two empirical constants, which defines longitudinal and transversal resistance factors. Integrating the procedure over all possible fiber directions that are defined by axially symmetric angular distribution density gives the resistance force acting on the entire layer of fiber and also pressure drop value. A comparison with obtained experimental data gives the values of transversal and longitudinal resistance factors. Their ratio, which approximately equals to 2, fits the findings of other publications