Abstract
The relationship between Reynolds' number of textile fibers and the drag coefficient of air has been studied by measuring the terminal velocity of fiber at the free dropping in the still air. The following results have been obtained :
1) When Reynolds' number of fibers is defined as Re= Ug d / v by using the diameter of a fiber as a specific size, the relationship between the drag coefficient C and Reynolds' number Re are decided experin entaly as follows :
for mono-fiber C=24/(2.75 Re0.756)
for bundle of fibers C =24/(193 Re2.00)
2) The drag coefficient of a mono-fiber and those of a ball and a pole have been compared. As the result, the drag coefficient of a mono-fiber is much smaller than that of a ball and very similar to that of a pole at the same Reynolds number.
3) It seems that the influence of the crimp of a fiber upon the drag coefficient is too slight to be seen.
