底吹过程中基于图像处理技术的气泡直径分布特性

Bubble size distribution in bottom blowing process based on image processing technology

为了获取底吹过程中气泡群直径的分布规律,采用高速摄影法及图像处理技术对水中气泡群直径进行提取与分析。首先,对原始图像进行预处理,将其转换为二值图像,通过设定圆形度范围将其分为单气泡、粘连小气泡、粘连大气泡3类,然后运用改进分水岭分割算法对粘连气泡进行分割处理,最后得到整个气泡群的直径分布。研究结果表明:随着气泡发生聚并破碎,水中小直径气泡居多,中等直径气泡和大直径气泡较少,气泡数量与气泡直径之间的关系可近似看作呈双曲线分布;随着气体流量增大,小直径气泡数量急剧增多,同时产生更大的气泡;气泡Sauter直径与最大直径均随着气体流量的增大而增大,气泡Sauter直径与最大直径的比值C稳定在0.72左右。

In order to obtain the bubble size distribution in bottom blowing process, the bubble size in water was extracted and analyzed based on high-speed photography and image processing technology. Firstly, the original images were preprocessed and converted into binary images. Then, the roundness of bubbles was extracted to separate bubble objects into solitary bubbles, small overlapping bubbles and large overlapping bubbles. The overlapping bubbles were segmented into solitary bubbles by using improved watershed algorithm. Finally, the bubble size distribution of all bubbles was extracted and analyzed. The results show that with the bubble coalescence and breakups, a large number of small bubbles coexist with a few numbers of medium bubbles and large bubbles in water. The correlation between the number of bubbles and bubble diameter has nearly a hyperbolic shape. With the increase of the gas flow rate, the number of small bubbles increases sharply, and the bubble is larger. The Sauter mean diameter and the maximum diameter increase with the increase of gas flow rate, and C which is defined as the ratio of Sauter mean diameter and the maximum diameter has an average value of 0.72.