Dynamics of a bubble column: Influence of gas distribution on coherent structures

The influence of the pattern of gas distribution on the dynamics of a bubble column is studied. LDA and glass fiber probe measurements were performed in a 15 cm column, aerated in well-controlled patterns using a special distributor. Superficial gas velocities of 0.015 m/s to 0.023 m/s were investigated. Uniform aeration gives very uniform gas distribution. The familiar large-scale circulation and structures are absent. Non-uniform gas-injection introduces dynamic structures in the entrance region. Large-scale structures are absent in the flow above the entrance region, independent of the gas injection pattern.