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This paper deals with the phenomenological study of flow regimes as they are influenced by changes in geometry and physical properties. The experiments have been performed with cylindrical tubes of up to 200 mm diameter using air injected into stationary water, of which the surface tension and viscosity were varied. The studies cover the range of surface tension reduced to half that of demineralised water, and of viscosity increased up to 10,000 times that of demineralised water. Independently of the diameter of the test cylinder for reduced surface tension only bubble flow, which changes immediately into foam flow, has been observed. The effect of the viscosity on the flow pattern is different. Flow patterns not yet reported in the literature have been observed. For example, at a low superficial gas velocity (2 x 1.0 E-3 m/s) and with a fluid viscosity of 300 mPas (300 times that of demineralised water) grape-like clusters dominate the flow regime. For fluid viscosities of 10,000 mPas and superficial velocities in the range of 0.1 m/s "meta-stable" bubble chains, bridged by channels allowing gas venting, form the observed flow regime. Its main characteristic is the regular building up and destruction of the chain into single slugs. The correlation between superficial velocity, void fraction and flow pattern is discussed.

Additional information

Authors: OSTER R, JRC Ispra Estab. (IT);KOTTOWSKI H M, JRC Ispra Estab. (IT);SCHROER P, JRC Ispra Estab. (IT)
Bibliographic Reference: Paper presented: International Symposium on Runaway Reactions, Cambridge, Massachusetts (US), March 7-9, 1989
Availability: Available from (1) as Paper EN 34624 ORA
Record Number: 198910379 / Last updated on: 1994-12-01
Original language: en
Available languages: en
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