The behaviour of gas-liquid foams has been the subject of extensive research in the past century because of the usefulness of liquid foams in industry. In this work we present new experimental and theoretical developments concerning flow and drainage behaviour of surfactant based liquid foams and films. The flow of free films and foam was studied in vertical tubes for different liquid properties. Measurements of the thickness of the lubricating layer on the wall and CFD simulation shows a relationship between the liquid thickness, liquid viscosity and pressure drop for the flow of free films. For foam flow, friction factors were determined for all systems and data lied remarkably on a unique line on the friction factor-Reynolds number plot and has a practical significance in that pressure drop can be calculated using a constant friction factor along a pipe of a constant cross section in any flow regime. An improved ER technique has been developed for accurate measurements of foam resistance, which includes the liquid layer at the wall. Traditional ER-methods for characterising the drainage of a wall-confined static foams do not take into consideration the effects of a substantial liquid layer established on the wall during drainage which transports a substantial amount of liquid. A method is proposed for the estimation of temporal as well axial variations of the wall liquid thickness inferred from the measurements of the local liquid holdup. A theoretical model is proposed for foam drainage based on the analogy of liquid flow through a packed bed of solid particles. A good agreement is obtained between theory and experiment on the basis of judicious estimations of foam cell size and shape factor.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:368426 |
| Date | January 2001 |
| Creators | Wiggers, Frank Norbert |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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