Bubble formation at a nozzle submerged in viscous liquids having yield stress

The effects of operating conditions on bubble volume formed from a nozzle s ubmerged in some viscous media with yield stress were experimentally invest igated. Pressure fluctuations in the gas chamber accompanied by bubble form ation as well as bubble growth curves were measured. By analysis of the tim e course of pressure change in the gas chamber, the dependency of the gas f low rate into the gas chamber and the chamber volume on the polytropic coef ficient of gas in the gas chamber was discussed. To simulate the bubble for mation at a single nozzle in a viscous medium having yield stress, the non- spherical bubble formation model was proposed. The calculated bubble volume s agreed relatively well with the experimental ones. (C) 2001 Elsevier Scie nce Ltd. All rights reserved.