Experimental Investigation on the Velocity Structure and its Effect on the Flow Patterns of Air-Water Two-phase Flow in a Horizontal Pipe

In order to investigate the behavior of air-water two-phase flow in a horizontal pipe, some series of experiments were performed to measure the velocity distribution in a horizontal pipe with PTV technique and the passing length and occurrence frequency of the air flow were analyzed based on the local measured velocity and electrical conductivity. A correlation between the velocity structure and the vertical distribution of air in the pipe was observed. On the basis of passing length and occurrence frequency, the flows were classified into bubble, plug, and elongated bubble in terms of bubble length to gain an understanding of flow patterns. From the results, it is possible to provide a guideline for predicting and controlling two-phase flow behavior in a large depth tunnel by investigating the characteristics of air-water flow in a horizontal pipe.