Effects of inlet condition on flow structure of bubbly flow in rectangular column


Effects of inlet condition on flow structure of bubbly flow in rectangular column

Akbar, M. H. B. M.; Hayashi, K.; Tomiyama, A.; Lucas, D.

Experiments on bubbly flows in a rectangular column are carried out to investigate effects of inlet condition on flow structure. An air diffuser having 35 nozzles is used. The inlet gas flow rates from 34 nozzles are uniform and the lift coefficients of bubbles are small at this flow rate, whereas the gas inflow from the remaining one nozzle is varied to change the sign and magnitude of lift coefficients. The main conclusions obtained are as follows: (1) bubbly flow in a bubble column is apt to be heterogeneous even with small non-uniformity in the distribution of gas inflow, (2) when the nozzle causing non-uniform gas inflow is located in the center of the diffuser plate and the inflow distribution is symmetric, heterogeneous structure is formed due to the lift-induced flow instability pointed out by Lucas et al., (3) when the nozzle causing non-uniform gas inflow is located near the side wall of the column and the inflow distribution is asymmetric, heterogeneous structure is induced by the Coanda effect, and (4) a multi-fluid model can predict the effects of non-uniform gas inflow on the formation of heterogeneous structure in bubbly flow.

Keywords: Bubbly flow; Flow instability; Bubble; Bubble column; Multi-fluid model

  • Contribution to proceedings
    8th World Conference on Experimental Heat Transfer, Fluid Mechanics, and Thermodynamics, 16.-20.06.2013, Lisbon, Portugal

Permalink: https://www.hzdr.de/publications/Publ-19240
Publ.-Id: 19240