Abstract: The bubble growth and detachment was recorded using a high speed video technology. The post-processing of photos was completed by Image-Pro Plus 6.0 software. The bubble shape variation during bubble growth under the condition of two kinds of different tube diameters was investigated. The experimental results show that the dominant force during bubble growth is different for different diameter tube. The increment of bubble aspect ratio from the small diameter tube with time is greater at first and then becomes smaller， while that from the large diameter one with time is firstly smaller and then greater afterward. Since the bubble detachment condition cannot be satisfied for the small diameter tube， the bubble bottom edge migrates towards liquid side. On the other hand， the bubble detachment condition can be reached for the large tube when the angle between gas-liquid line and solid-liquid line is smaller than the contact angle， therefore the bubble bottom edge cannot migrate towards liquid side. The critical bubble aspect ratio for detachment of 3.80mm bubble is slightly larger than that of 9.28mm bubble.

Key words: gas-liquid reactor;bubble growth, bubble detachment, bubble shape