LOCAL-SCALE NUMERICAL SIMULATION OF AN AIR-WATER FLOW IN A TRIANGULAR TUBE BUNDLE IN TO PREDICT FORCE SPECTRA

In nuclear power plant steam generators, two-phase crossflows can induce tube vibrations or wear. Over the past decades, experimental campaigns mainly focused on the resulting vibrations, neglecting other parameters such as the void distribution. This has limited our understanding of flow pattern transitions and their influence on force spectra trends. A recent literature review proposed a concatenated flow pattern map for two-phase flows in triangular tube bundles. This map revealed inconsistencies in the transitions between two-phase flow patterns for several experiments. Thus, it is of interest to well understand local two-phase phenomena and the role played by the gas size distribution. To achieve this, local-scale numerical simulations, i.e. CFD simulations, were coupled with the dedicated local-scale experimental campaign. The present paper is dedicated to the numerical validation of a two-fluid model, designed to simulate the whole range of void fraction from 0% to 100%. It also aims to improve the understanding of 3 tests conducted on the TITAN experiment, an air-water facility with a triangular tube bundle at CEA.