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Mechanisms of foam generation in glass bead packs

Conference ·
OSTI ID:6974614

The fundamental, pore-level mechanisms of foam generation are investigated in monodisperse bead packs. First, direct visual observations identify the following generation mechanisms: lamella leave behind, gas-bubble snap off, and lamella division. Then, to ascertain the relative importance of these mechanisms, quantitative experiments are pursued on the role of bead-pack permeability (bead sizes from 0.25 mm to 1 mm), gas-phase velocity (0.001 cm/s to 0.8 cm/s), gas-phase fractional flow (0.60 to 1.0), permeability variations, and surfactant type (SDBS, SDS, Chevron Chaser SD1000, and Suntech IV 1035). The authors discover a critical velocity, above which a ''strong'' foam is generated and below which only ''weak'' foam is formed. The snap-off mechanism is the primary mechanism responsible for the formation of the strong foam. A simple model, based on the concept of a ''germination site'', is developed to predict the onset of snap off at higher gas velocities. New experimental data obtained in the homogeneous glass bead packs for the critical capillary number necessary to form a strong foam are in excellent agreement with the proposed germination-site model.

Research Organization:
Univ. of California
OSTI ID:
6974614
Report Number(s):
CONF-861080-
Country of Publication:
United States
Language:
English