Macroscopic mass and momentum balances have been used to predict the unsteady behavior of gas-liquid slug flow through vertical pipe. Equations have been developed to predict the time-dependent pressure drop along the pipe as well as the time-averaged pressure drop. The results of the analysis indicate that the gas bubble lengths and frequencies of generation must be known before the pressure drop can be predicted as a function of time. In this work the bubble generation was specified in two ways: by experimental measurement of the bubble lengths and frequencies of generation from an optical technique developed for this purpose, and by assuming a periodic generation of gas bubbles of uniform length. The comparisons between predicted and measured pressure drops (both time dependent and time averaged) are satisfactory and appear to support the theoretical model. An extension of the results obtained in light of the published, information on solid-gas and immiscible liquid-liquid systems in slug flow permits the introduction of generalized concepts of slug flow behavior in two-phase systems.
In a large number of engineering operations where vertical, cocurrent, two-phase flow occurs, a particular flow regime termed slug flow is observed. The slug flow