Measurement of Thickness of Foam layer and Entrance Region in a Bubble Column using Image Processing Technique

Abstract

Photographic method is a direct method for study of bubble behavior. Hydrodynamic study in a rectangular bubble column (0.37m X 0.2m X 0.02m) for air-water system was studied using photographic technique by recording movie at 120fps. Image processing tools were applied to measure regions of gas-liquid dispersion, entrance, foam layer and bubble-bursting were identified. The foam layer thickness showed maxima at Ug = 0.1 m s-1 . It decreased with increasing static bed height. The width of entry region also passed through maxima, though it was not sharp. The width of entry region increased with increasing settled bed height. Gas holdup measured in terms of pixel density deviated from experimental values with increasing superficial gas velocity due to overlapping bubbles. The average gas holdup decreased with increasing static bed height.