Air/water two-phase flow' in a horizontal large-diameter pipe. 1st Report. Flow regime.

Abstract

Experiments on air/water two-phase flow in a comparatively large and long horizontal pipe of 210mm in diameter and 30.5m in length were conducted at atmospheric pressure to investigate flow characteristics with emphasis on the stratified-to-slug flow transition. It was pointed out that superficial velocities of gas and liquid such as those used in the Mandhane flow regime map are not adequate to consistently represent the stratified-to-slug flow transition since a void fraction in the pipe is affected by the pipe diameter and the distance from the pipe exit. The stratified-to-slug flow transition is well predicted with the Taitel and Dukler correlation modified by multiplying 0.5, in which the local void fraction and velocities are used. The void fraction needed in the correlation can be calculated from the momentum equation of the liquid phase alone by neglecting the gas flow for smooth stratified flow. However, the gas flow cannot be neglected for the wavy stratified flow.