Pressure gradients of concurrent upward air-water flow have been measured in a 25.4mm internal diameter vertical test section over a range of superficial air and liquid velocities. Several sub-regimes of annular flow (pulse/disturbance wave, ripple wave, partial wetting, and rivulet) were observed with pressure gradients and images recorded. A new flow regime map has been drawn and compared with previous work. Revised sub-regime boundaries are proposed, which will guide further development of future models of annular two-phase flow.
An understanding of the behaviour of gas-liquid systems is important in a number of areas, including the production of natural gas where liquid influx into the wellbore can eventually impair well performance. While several unified mechanistic models for two phase flow are available, many treat annular flow as a single regime. The objective of this on-going work is to seek a more detailed description of annular flow by distinguishing its sub-regimes. The first part of this program has been to identify and map those sub-regimes.
One of the earliest visual studies of multiphase flow can be found in the work of Versluys (1, 2) who identified at least three different flow regimes in a gas liquid system, for which he also recorded motion pictures:
a "foam condition"
a "mist condition"
an intermediate condition of gas bubbles where "the shape of a jelly-fish is approached."
A flow loop at the University of Alberta is being used to investigate gas-liquid behaviour in vertical co-current upward flow, with the focus on the annular regime. The objective is to gain a sufficient understanding to produce new models of this regime.