DRAFT

Abstract The present work focuses on the measurements of bubble properties in heterogeneous bubbly flows in a square bubble column. A four-point optical fibre probe was used for this purpose. The accuracy and intrusive effect of the optical probe was investigated first. The results show that the optical probe underestimates bubble properties, such as, bubble velocity, local void fraction. The presence of the probe in the bubble column influences the local flow conditions. Particularly, when the probe is placed close to the liquid surface, this influence is more pronounced. Furthermore, two methods determining interfacial area were compared. The results from both methods agree quite well at low superficial gas velocity, whereas large discrepancies are found when superficial gas velocity increases. Finally, effect of column height on bubble properties was studied. No significant difference was found for the three investigated columns