THEORETICAL-ANALYSIS OF FLOW CHARACTERISTICS OF MULTIPHASE MIXTURES IN A VERTICAL PIPE

This paper is concerned with the theoretical analysis to obtain the fl ow characteristics of multiphase mixtures in a vertically fixed air-li fting pipe. In this present investigation, the case is treated where a transition process from a solid-liquid two-phase mixture flow to a so lid-gas-liquid three-phase mixture by injecting gas-phase into the upr iser through a gas injector is present. The system of equations govern ing the liquid-solid two-phase mixture flow consists of two mass conse rvation equations, two momentum conservation equations and a requireme nt for two phase volumetric fractions. Again, the gas-liquid-solid thr ee-phase how field after the position of gas injection is solved by th ree mass conservation equations, three momentum equations, a gas equat ion of state and a requirement for the individual phase volumetric fra ctions. The transitions of the flow pattern of gas phase from bubbly t o slug flows and from slug to churn hows are taken into account in the system of equations governing the three-phase flows. In order to veri fy the validity of the system of governing equations accounting for th e how patterns transitions of gas-phase, the flow characteristics calc ulated on the basis of the present theoretical model have been compare d with experimental data measured by the other investigators. As a res ult, we have found that the present theoretical model built up in this study gives a good fit to the experimental data obtained by several i nvestigators. Furthermore, we have demonstrated that the present model is capable of predicting the maximum solid/liquid volumetric flux. (C ) 1998 Elsevier Science Ltd. All rights reserved.