Structural Developments of Turbulent Two-Phase Flow in Large Pipes

Abstract

In connection with the thermohydraulic problems of two-phase flow that may be encountered under certain operating conditions in piping systems containing heat sources and sinks such as a CANDU reactor heat transport systems, the present work has been carried out analytically and experimentally. In general this study is devoted to investigate some of the turbulent characteristics of both the cocurrent air-water two-phase flow and single phase flow, flowing in large pipes with horizontal orientation.

Pitot tube associated with hot film anemometry have shown to be an adequate measurement system in turbulent dispersed two-phase flow. Based on such an application,a practical semi-empirical formula has been developed to predict local mixture velocity as a function of differential head read by Pitot tube, local void fraction, flow pattern constant, gas-liquid properties,momentum transfer factor and two-phase flow quality.

The structural developments of the dispersed mixture velocity was studied along a straight horizontal PVC run and expressed in terms of the radial distance and the pipeline length. In addition,a unique correlation has been introduced in this paper to determine the local mixture velocity in terms of radial, streamwise distance, two-phase flow quality, gas and liquid densities. Similar correlation is presented to predict the local developments of the void fraction.

In addition to those normalized correlations, hypothetical interpretations of the experienced phenomena have been presented.

Generally, it was found that the mixture velocity is significantly influenced by the volumetric mixing ratio of both phases.

Finally, conclusions have been drawn in the special case of both turbulent single and two-phase flow.