Abstract: Influences of various parameters such as liquid inlet flow, feeding height, inlet aperture, diameter of tube and inclined angle on the wetting ability of liquid film were studied. Image processing method was adopted to measure wetting length of liquid film on the plain tube with different parameters. The experimental results showed that with the increase of the flow rate, the wetting ability of the liquid film stays the same after reaching the peak. When the feeding height is investigated, the flow pattern needs to be considered. The effect of feeding height on wetting ability is negligible with the flow pattern of columnar flow. Wetting ability decreases firstly then remains unchanged with increasing feeding height under columnar-sheet flow regime. Shortly after sheet flow, wetting ability reaches saturation. As for increasing the inlet aperture, the flow pattern needs to be considered. Wetting ability increases first and then decreases under columnar flow, but the variation is relatively small. When flow pattern is transformed into columnar-sheet flow or sheet flow, liquid wetting ability will fall. Under the condition of a certain flow rate, the larger the diameter is, the larger the wetting area of the liquid film is, but the worse the wetting ability is. When the experimental tube is not horizontally placed, the change regulation of wetting length is no longer symmetrical with the liquid inlet column, but the lower part is stronger and the upper part is weaker.

Key words: falling film, wetting ability, distributor, flow, measurement, laminar flow

摘要： 在不同进液流量、进液高度、进液孔径、管径和倾斜角下，用图像法测量了光滑圆管外壁液膜湿润长度，研究了各参数对液膜湿润能力的影响. 结果表明，随进液流量增大，液膜湿润能力先增大后稳定在一个固定值. 研究进液高度对湿润能力的影响时需考虑液膜的流型，流型为柱状流时，液膜进液高度对液膜湿润能力的影响较小；流型为柱状?片状流时，随进液高度增大，液膜湿润能力先减小后不变；流型为片状流时，液膜湿润能力达到饱和. 研究进液孔径对湿润能力的影响时需考虑液膜的流型，流型为柱状流时，液膜湿润能力随进液孔径增大先增大后减小，变化幅度较小；流型为柱状?片状流和片状流时，液膜湿润能力随进液孔径增大而减小. 一定流量下，管径越大，液膜湿润表面积越大，湿润能力越差. 受倾斜角度的影响，液膜湿润长度不再沿进液柱对称分布，湿润能力出现下强上弱的分布规律.

关键词: 降膜, 湿润能力, 布液器, 流动, 测量, 层流