Air Flow Through Textiles at High Differential Pressures

摘要

Air flow through fabrics at ralatively high differntial pressures is studied both experimentally and theoretically. An extensiion of a previous model fro fluid flow through a bed a fibes takes into account the geometric irregulatities and deflection of the fibers, successfully predicting that the pressure drop acorss the fabric is a linear function of the air flow rate up to the pressure corresponding to critical flow conditions. It also correctly predicts values for the elastic moduli of the vaious fibers. The influence of fiber swelling induced by wetting on air permeability is examined. At high differential pressures (55 kPa), a decreased air flow rate is found only for wool fabrics. Under the conditions of the standard fabric air permeability test (differential pressure 12.3 Pa), water blocking the channels in the wet fabric is not removed, so the air premeability is much less than that for the conditioned fabric.