The Development of Electronic Instrument for Studies on the Transient properties of Capillary penetration process and its Application

设计了一种新的仪器，它可以准确地测量液体在织物等多孔材料中的毛细渗透速率和高度。当两个平行的平板电极浸泡在乙醇水中时，电极之间的电容增加与电极之间的乙醇水高度成正比。该电路用于检测放置在两个平行板电极之间的垂直布条中的水位，并给出电容与水位之间的线性关系。液体在织物中上升的过程，因此从与液体接触的第一时刻起，电容的增加就会被自动记录下来。这种液位-电容转换方法响应速度很快，可以实时记录液体的运动情况。水和乙醇在织物中的毛细渗透实验曲线与基于宏观能量平衡的Szekely-Neumann-Chuang理论定量地一致，解释了毛细渗透的早期稳定性。在实验测量的基础上，用理论估算了纤维的表面特性和织物的几何效应。

A new instrument has been designed which gives an accurate measurment of the rate and height of capillary penetration of liquid in a porous material, such as fabrics, from the very initial moment of contact with water.When two parallel plate electrodes are immersed in water of ethanol, the increase of capacitance across the twin electrodes is directly proportional to the height of water of ehtanol between the electrodes. The circuit was used to detect the level of water contained in a vertical strip of fabric put between twin parallel plate electrodes and to give liear relation between capacitance and water level. The progress of liquid rise in a fabric, thus the increase of capacitance is recorded automatically from the first moment of contact with the liquid. Such a liquid level-capacitance conversion metnod has a very quick response, and so we can obtain a real time record of the movment of liquid.Experimental curves obtained on capillary penetration of water or ethanol in fabrics was proved to be in quantitative agreement with Szekely-Neumann-Chuang theory which was derived on the basis of macro energy balance, for the interpretation of the very early stabes of capillary penetration. Thus on the basis of experimental measurements, the fiber surface charcteristic and the fabric geometry effect were estima ted by using the theory.