Effect of walking speed on the evaporation coefficient of defence workwear

The ripstop fabrics are highly appreciated in the military and defence workwear. One of the qualities requirements in defence clothing is quick evaporation. The effect of the wearer’s walking speed on textile fabric evaporation during capillary rise was investigated in this study. To achieve this, two steps were taken: modelling the capillary considering evaporation and estimating the coefficient of evaporation using a program designed for image analysis. The walking speed was simulated by varying the air velocity from 0 m/s (non-walking) to 1 m/s (walking) and 2 m/s (running). Results conclusively demonstrated that the evaporation coefficient is directly relational to the water vapour in the surrounding air layer and is highly dependent on the aeration rate. Furthermore, liquid equilibrium front level and capillary diffusion were found to be inversely proportional to the walking speed. The walking speeds affected the indirect water amount on the fabrics and it was more difficult to evaporate liquid from the 100% cotton compared to 65% polyester/35% cotton/