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Chemical Engineering Science, Vol.59, No.1, 247-258, 2004
The impact of external electrostatic fields on gas-liquid bubbling dynamics
The effect of an applied electric potential on the dynamics of gas bubble formation from a single nozzle in glycerol was studied experimentally. Dry nitrogen was bubbled into glycerol through a nozzle having an electrified tip while pressure measurements were made upstream of the nozzle. As the applied electric potential was increased from zero, bubble size reduced, bubble shape became more spherical, and bubbling frequency increased. At constant gas flow, bubble-formation exhibited a classic period-doubling route to chaos with increasing potential. We defined an electric Bond number assuming that both the liquid and gas phases are conducting. This is in contrast to previous studies where one phase was considered a perfect conductor and the other one a perfect nonconductor or insulator. Although electric potential and gas flow appear to have similar effects on the period-doubling bifurcation process for this system, the relative impact of electrostatic forces, as measured in terms of electric Bond number for conducting liquid and gas phases, is smaller. However, the relative impact of electrostatic forces for the case of insulating liquid and conducting gas phases is comparable to flow forces. Further data collection is required for different nozzle geometries and liquid column heights in order to verify the relative impacts of electrostatic and flow forces, and would allow us to ascertain if electrostatic potential is a feasible manipulated variable for controlling this system. (C) 2003 Elsevier Ltd. All rights reserved.