The formation of foam by the co-current flow of aqueous surfactant solution (Triton X-100, 0.2% by wt. in distilled water) and air, in sand packs, has been studied by passing the foam into a thin glass cell and measuring the sizes of the bubbles from a photographic record. It was found that, other variables being constant, the mean bubble size falls with increase of sand pack length, for very short packs, but levels off at long lengths until it becomes independent of length, at lengths greater than 4×10-2 m. The absolute size of the bubbles was always about twice the grain diameter, but also depended somewhat on the foam quality and foam flow rate. When a nitrogen foam, comprising small bubbles, formed by the co-current flow of gas and an aqueous solution of Genopol LRO (0.14% by wt.) through a bed of fine sand was passed through a bed of larger glass beads, the bubble size of the foam increased. These observations all support the hypothesis that the flow process is a dynamic one in which the foam lamellae continually undergo rupture and reconstruction during their passage along the pore system, at rates which are determined by the pore geometry, as well as by the foam quality, the foam flow rate, and the rheological properties of the lamellae. Decrease in foam quality tends to give rise to decrease in foam bubble size, other variables being held constant.
|Number of pages||18|
|Journal||International Journal of Engineering Fluid Mechanics|
|Publication status||Published - Sep 1992|