Abstract
Two phase flows in large diameter pipes have immense importance in a wide variety of industrial applications. As a first approximation for the prediction of a two-phase flow and as a beginning for the development of more complex models, the drift-flux model is often used to characterize and predict flows for many geometries and flow conditions. In this chapter, the flow characteristics in flows in large diameter pipes are illustrated based on the experimental data. The flow regimes and their transition criteria are discussed. The existing drift-flux models are summarized, their strengths and weaknesses are noted and the data that can be used to evaluate these models are presented. Based on the flow regime transitions in large diameter pipes, all of the available drift-flux models are evaluated systematically in both low (bubbly) and high (cap and churn-turbulent) void fraction flows. The drift-flux type correlations of Hibiki and Ishii [14] and Kataoka and Ishii [24] are found to be able to give the best predictions for the existing low and high void fraction databases respectively and are recommended for void fraction predictions in flows in large diameter pipes