A Criterion of Negative Frictional Pressure Drop in Vertical Two- Phase Flow

Abstract

Pressure drop is an important parameter in the study of gas-liquid two-phase flow (Beggs and Brill, 1973). The phenomenon of negative frictional pressure drop is observed in an experiment. In the process of the experiment, it is necessary to research the law of negative pressure drop. In this paper, the two-phase flow experiment is carried out in a vertical pipe of 60mm in diameter and 8m in length. The apparent liquid velocity is from 0.08 to 0.20 m/s, the apparent gas velocity is from 1 to 19 m/s. Air and mineral oil are used as the working fluids, and the viscosities of the oil are 25, 50, 70, 150, and 200 cp, respectively. The multiphase flow test platform is used to research the negative pressure drop. A criterion is given to judge the phenomenon of negative frictional pressure drop; the smaller the apparent gas-liquid velocity, the greater the influence of viscosity on the negative frictional pressure drop.