Vibration analysis of a rotating propeller in lead-bismuth eutectic through fluid-structure interaction simulation

In this work, the vibration characteristics of a propeller rotating in lead-bismuth eutectic (LBE). are studied using fluid-structure interaction (FSI) simulations, which are developed in parallel with an experiment performed at the Belgian Nuclear Research Center (SCK CEN). Both the simulations and the experiment are part of a larger campaign to develop a methodology for characterizing the vibrations in primary pumps of nuclear reactors using heavy liquid metal
coolants. These coolants are of interest due to their use in Generation IV nuclear facilities such as MYRRHA , using LBE as a coolant, and lead fast reactors (LFR), using lead. The high density of this liquid can significantly alter the vibration characteristics compared to when used in air and water, and introduce mode coupling, a phenomenon that is not yet sufficiently understood in the context of heavy liquid metals. The simulations allow for an extensive analysis of the different vibration modes. The investigated propeller consists of three symmetrical blades and is operated at different rotational speeds. First, the structural eigenmodes are calculated in vacuum, using the finite element method (FEM). Afterwards, the fluid and propeller are combined in a two-way coupled FSI simulation. For each mode a particular excitation force initially is applied to the structure to facilitate the extraction of vibration characteristics by
analyzing the free response of the system. This allows to extract the Eigenfrequency and damping ratio of that mode in LBE. The results show that this methodology allows for a prediction of the measured vibration response in the test setup.