CFD Simulation of Water Hammer Induced by Condensation Using an Improved Phase Change Model

Abstract A computational fluid dynamics (CFD) based approach using FLUENT is applied to investigate the phenomenon of condensation-induced water hammer (CIWH) caused by direct contact condensation. In these simulations, the two-phase interface is explicitly tracked using the volume of fluid (VOF) method, and a hybrid heat transfer coefficient (HTC) model based on surface renewal theory is employed for interface heat transfer. The HTC model is implemented through user-defined functions (UDFs). The simulation results are compared with experimental data obtained from the PMK-2 facility of the VVER-440/312-type nuclear power plant in Budapest, Hungary. The results demonstrate that the model aligns well with the measured temperature field, as well as the timing and magnitude of pressure peaks. This CFD approach can be utilized for prediction and prevention of CIWH.