Abstract
This document summarizes the work to validate the droplet entrainment and de-entrainment models, as well as two-phase closure models in the CTF code [1] by comparison with experimental data obtained at Risø National Laboratory [2]. CTF is the modernized version of the subchannel code, COBRA-TF [3], being jointly developed by Oak Ridge National Laboratory and North Carolina State University for applications in the Consortium for Advanced Simulation of Light Water Reactors (CASL). The Risø data included a series of more than 250 steam/water experiments that were performed in both tube and annulus geometries over a range of various pressures and outlet qualities. Experimental conditions were
set so that the majority of cases were in the annular/mist flow regime. Measurements included liquid film flow rate, droplet flow rate, film thickness, and two-phase pressure drop.
CTF was used to model 180 of the tubular geometry cases, matching experimental geometry, outlet pressure, and outlet flow quality to experimental values. CTF results were compared to the experimental data at the outlet of the test section in terms of vapor flow fractions, and entrained liquid flow fractions, and pressure drop per unit length.
