Abstract

Air-water flow at ambient conditions in a vertical pipe with an inner diameter of 51.2 mm is investigated. An electrode wire-mesh sensor enables the measurement of the phase distribution with a very high resolution in space and in time. Local bubble size distributions are calculated from the data. The measurements were done in different distances from the gas injection device. As a result, the development of bubble size distributions as well as the development of the radial gas ftaction profiles can be studied. It was found, that the bubble size distribution as well as local effects determine the transition from bubble flow to slug flow. The data are used for the development of a model, which predicts the development of the bubble size distribution and the transition from bubble flow to slug flow in the case of stationary flow in a vertical pipe.