Interfacial Area Transport Equation Evaluation Methodology in Large Diameter Pipes

Abstract

Two-phase flows in large diameter pipes are significant throughout nuclear power systems for accident analysis and, in BWRs, steady-state performance analysis. Currently predictive computer codes use static, flow-regime-dependent models to predict the interfacial area concentration, which describes the interfacial geometry of a two-phase flow. To improve the ability of these codes to predict the behavior and development of two-phase flows, it has been proposed that the Interfacial Area Transport Equation (IATE) be used. The IATE is well- developed for small diameter pipes, or those in which stable slug flows can exist, however for large diameter pipes where stable slug bubbles cannot form very little data is available. Therefore an experiment has been undertaken to measure the local profiles of various two-phase flow parameters at several axial positions in large diameter pipes of varying diameters. The results are presented here along with a method for evaluating the performance of the IATE and the results of the IATE performance evaluation for the experimental data.