水平与微倾斜管内间歇流中长气泡的形态特征

利用双平行探针技术和摄像方法对水平和近水平微倾斜管内长气泡的形态特征进行了实验研究.实验结果表明气泡头部以及气泡体的形态特征取决于气液混合Froude数和管道倾角，而尾部特征还与气泡长度有关;小气泡通过单纯水跃面的长气泡尾部向液塞区弥散，而具有阶梯状尾部结构的长气泡并不向液塞区弥散小气泡，所以气泡尾部结构特征的变化决定了弹状流向段塞流的转变;管道倾角对长气泡形态特征有显著的影响，下倾管内的长气泡在低Froude数时出现头尾倒置现象，同时下倾管内的长气泡比上倾管更易保持阶梯状的尾部结构，所以下倾管的弹状流区比上倾管宽.

Shape of long bubbles in horizontal and inclined intermittent flows

This paper presents the results of an experimental study of the shape of long isolated bubbles similar to those observed in horizontal and inclined intermittent flows by using parallel-wire probes and photography. It was shown that the shape of bubble nose, body and tail depended on Froude number and pipe inclination angle, whereas the shape of bubble tail depended on bubble length as well. The photographic study showed that bubble tail changed from staircase pattern to hydraulic jump, corresponding to the transition from plug to slug flow, with increasing Froude number and bubble length. The inclination angle had strong influence on the shape of tail, which would lead to the transition from plug to slug flow. The transition in an upward pipe occurred at lower superficial gas and liquid velocities compared to that in a downward pipe. The bubble shape from nose to tail was reversed in downwardly inclined pipe at low Froude number.