Abstract
The effects of liquid viscosity on the rising velocity of a large gas bubble in a stagnant liquid, and on the flow parameters of slug flow were experimentally investigated using a 19.2mm diameter vertical tube with air and liquid as working fluids. The liquids used in the present experiment were water and glycerol solutions, and the kinematic viscosity of these liquids ranged from 0.83×10-6 to 15.5×10-6m2/s. The important parameters in slug flow such as the rising velocity of large gas bubbles, liquid slug length, liquid film thickness around large gas bubbles etc., were measured. As a result, it is clarified that the rising velocity of a large gas bubble in a stagnant liquid decreases only slightly with increasing liquid viscosity. On the other hand the rising velocity in flowing liquid, i.e., in slug flow increases with increasing liquid viscosity. These results are discussed in relation to the liquid film thickness around large gas bubbles. Furthermore, the mean values of gas and liquid slug lengths and the ratio of their standard deviations to mean values of their length are examined by paying attention on the effect of liquid viscosity.