|Budget Amount *help
¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1994 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1993 : ¥1,800,000 (Direct Cost : ¥1,800,000)
Attention was paid to the trasient phenomena of liquid penetration in radial direction into porous substances like paper and cloth without depending on external force, and the measuring instrument of tracking this by electric capacitance method was made for trial. On one of two parallel plate electrodes which were set horizontally facing each other, a small hole was drilled, and through it, water was supplied continuously from a liquid vessl. A sample was put between both electrodes, and rectangular waves were applied. From the moment of coming in contact here, the electric capacitance changed sharply. This was recorded, and the penetration characteristics were analyzed. The transient penetration speed of water shorter than 1 s for filter paper (5mm radius) is controlled by the roughness of the surface with which water comes in contact, and it is larger in rough surfaces than in smooth surfaces. The relation of the diameter of water supply holes with penetration speed examined, and as
the suitable diameter, 3mm was decided. As the diameter of the holes was larger, the penetration speed in transient period was higher, and the equilibrium penetration quantity was attained earlier. For the radial penetration of a liquid drop on paper, the relation of the penetration A with time t is given by A=Kt^n, where K is a constant related to the properties of paper and liquid. Thereuopn, when the experimental results on the relation of A and t were plotted by both logarithmic scale, it was found that those consisted of three straight lines with different gradient n. First, in the transient period of shorter than 0.5 s, about n=1.8 was detected and it is considerably larger value than the steady state which was published so far. Subsequently, there was the region of n=0.9, and the region of n=0.3 followed. It was known that n and its duration become the indices for determining the penetration characteristics of samples.
ろ紙(半径5mm)に対する1秒以下の水の過渡浸透速度は、水の接する面の粗さに支配され、粗面の方が平滑面より大きい。水の補給孔の直径と、浸透速度の関係を検討し、適当な直径として3mmとした。細孔の直径が大きいほど過渡期の浸透速度が大きく、速く平衡浸透量に達する。 紙への液滴の半径方向の浸透にたいして、浸透面積Aと時間tの関係は、A=Kt^nであたえられる。ここで、kは紙や液体の性質に関する定数である。そこで、実験結果について、Aとtの関係を両対数プロットすると、3つの異なる勾配(n)をもつ直線からなることがわかった。まず、0.5秒以下の過渡期では、n=1.8前後が検出され、これまで発表されている定常状態よりかなり大きい値である。続いて、n=0.9の領域であり、この値はMarmurの定常状態(液体の補給が無限)でのnと一致するさらに、n=0.3の領域が続く。この値は、Marmur(液体の補給を停止)やKissa(液滴)の得た値と一致するが、本結果の場合試料サイズが有限であるため、試料境界に近づいて浸透速度が減速するために生じたものである。nやその持続時間は、試料の浸透特性を決める指標になることがわかった Less