[in Japanese]

View full abstract

The motion of fibers in a fluid is a fundamental phenomenon for the textile technology. In this paper, a slender body is used as the simplest model of a single fiber. Equations of motion of a slender body in the flow have been de rived and they have been applied to the falling motion in horizontal uniform flow. Influences of fluid velocity and slender body length on the behaviors of the body have been investigated by numerical calculation. The obtained results are as follows :
(1) A slender body, which begins to move in an inclined direction to the vertical, approaches to the vertical direction immediately after the beginning of the motion. Thereafter, its direction of the motion slowly approaches to the horizontal direction and the trajectory of its mass center has an inflection point. then the body begins to approach to the vertical direction again. Finally it approaches to the horizontal posture asymptotically, it falls vertically at the same constant speed as that in still liquid and moves horizontally at the same speed as the fluid velocity without rotation.
(2) The fluid velocity influences the motion of the body only within the small region after the starting in motion (until the body inclines to about 15° to the vertical for 30 mm in length). Beyond this region the relative translation al motion of the body to the fluid is independent of the fluid velocity. Therefore, the body rotation is also unaffected by the fluid velocity. And there is a tendency for fluid velocity to have more remarkable influences on the behaviors with decreasing length.

View full abstract

In this paper, equations of a slender body motion in the flow which were derived in the previous paper have been applied to the falling motion in a fully developed horizontal flow through a rectangular duct. Influences of the fluid velocity and a slender body length on the behaviors of the body have been investigated by the numerical calculation.And the behaviors in the flow with velocity distribution in a vertical direction have been clarified by comparison with the results in a horizontal uniform flow. The obtained results are as follows :
(1) The relative translational motion of the body to the fluid in a middle region of the duct is independent of the fluid velocity similarly to that in the uniform flow, because in this region there still remains a relatively flat velocity distribution even under fully developed conditions. However, in boundary layers developed along the wall with large velocity gradient, especially in the bottom boundary layer region the direction of the motion of the body mass center rapidly approaches to the vertical direction. And the body with large length also rotates its posture into the vertical in this region.
(2) When the body moves in the boundary layer regions, the change of horizontal velocity and angular velocity against the posture differs from the results in the uniform flow. It is evident that the fluid velocity and the body length influence on the body behaviors more strongly in the fully developed flow than in the uniform flow. However, the dependence is observed between the body posture in the bottom boundary layer region and the duct height, so that it needs to consider the effect of the rectangular duct height in discussing the influences of different factors.

View full abstract

A determinative method was investigated for fiber content of blended fabrics of wool by using an infrared spectrum technique. The samples examined were wool/polyester, wool/acrylic and wool/nylon6 blended fabrics.The quantitative analysis of infrared spectra was carried out accurately by an infrared spectrophotometer by using KBr tablets. The blended ratio of two-component blended fabrics can be estimated by observing infrared spectra obtained by changing the fiber content systematically and by the calibrated curve between blended ratio and absorbance ratio [KB= (D₁/D₁+D₂) ×100] obtained from properly selected two key bands. Values obtained correlate well with calculated value by experimental equation derived from the leastsquare method. Thus, this method is recognized to be very useful for determining fiber content of blended fabrics.

View full abstract

As described in part 1, an infrared spectrum technique is interesting as simple method for determination of the fiber content of blended fabrics. This method was investi gated for blended fabrics of cellulosic fibers. The samples examined here were cotton/polyester, rayon/ployester, cotton/acrylic, cotton/vinylon, cotton/polypropylene, cotton/nylon6 and rayon/nylon6 blended fabrics.
Thus, this method was recognized to be very useful for the determination of the fiber content of blended fabrics in the above combinations, as well as wool fabrics.

View full abstract