THE EFFECT OF WIND ON THE THERMAL RESISTANCE OF CLOTHING WITH SPECIAL REFERENCE TO THE PROTECTION GIVEN BY COVERALL FABRICS OF VARIOUS PERMEABILITIES

Abstract

The thermal resistance of a pile fabric uncovered and covered with thin fabrics of various permeabilities was measured under different conditions of wind velocities and wind direction. Wind velocities up to 30 m.p.h. were used and tests were carried out with winds striking the surface of the material at 0°, 30°, 45°, and 90°. The permeabilities of the covers varied between 0 and 193 cu. ft. per sq. ft. per min., under a pressure difference of [Formula: see text] in. of water across the fabric. The effects of varying the conditions of the thermal resistance of the boundary air layer are discussed and corrections applied to the results for the resistance of this air layer. The results show that for low wind velocities, the permeability, within wide limits, is relatively of little importance, but with higher wind velocities it is advantageous to employ a covering fabric of as low a permeability as possible.