Effects of orifice angle and surface roughness on the bubbling-to-jetting regime transition in a bubble column

Submerged gas injection into liquids is a widely applied processing technique. The main objective of the current study was to determine the effects of orifice angle and orifice surface roughness on the bubbling-to-jetting regime transition in a bubble column. The bubbling behaviors at single-orifice distributors were investigated over a wide range of orifice gas velocities. The pressure fluctuations in the plenum and high-speed image sequence of the bubble emerging process at the orifice were recorded in experiments. Both orifice angle and orifice surface roughness were found to have significant effects on the regime-transition velocity between the bubbling and jetting regimes. Models were also developed by incorporating those available in the literature with the experimental results obtained in the current study.