The upward vertical flow of air‐water mixtures: III. Effect of gas phase density on flow pattern, holdup and pressure drop

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Abstract
Results of measurements of pressure drop and holdup are reported over a range of air and water rates for the upward vertical flow of air‐water mixtures in a 1.50 inch I.D. tube with average air densities ranging from 0.092 to 0.552 lb./ft.3 Superficial water velocities were between 0.0695 and 7.35 ft./sec.The data are analyzed by the method first suggested by Govier, Radford and Dunn and later used by Govier and Short. This involves the division of the flow range into four regimes on the basis of the pressure drop curves (to aid correlation of flow pattern and holdup data) and the separation of the unit pressure drop into hydrostatic and irreversible components. A superficial friction factor is calculated from the irreversible component of the unit pressure drop.The average density of the gas phase has a more or less marked effect on all three regime transitions. The transitions all shift similarly to lower air‐water discharge volume ratios with increasing gas phase density. While the flow patterns were not directly observed in the investigation here reported, the flow pattern transitions would be expected to behave similarly.Over the range investigated, the gas phase density has little or no effect on the superficial friction factor. The holdup ratio is unaffected by the gas phase density in Regimes I and II but is significantly affected in Regimes III and IV.