MYRRHA is a flexible fast-spectrum research reactor under design at SCK•CEN, the Belgian Nuclear Research Centre. The primary coolant is Lead Bismuth Eutectic (LBE). Research on cavitation erosion in liquid LBE is crucial to confirm the safety of MYRRHA. Cavitation is an important phenomenon of pumps hydrodynamics, which can significantly accelerate erosion of pump parts and lead to their rapid destruction.
Figure 1: Result of cavitation on a pump impeller.
Currently, there is a gap in knowledge of the characteristics of cavitation in liquid LBE, conditions and factors affecting its appearance such as:
The experimental data will characterize the cavitation depending on various factors. This data can be used as input in the design of the MYRRHA pumps.
This research aims at better understanding the cavitation parameters to estimate the required Net Positive Suction Head (NPSH) for pumps operating in liquid LBE and to evaluate the possible cavitation impact on pump parts.
The proposed methodology consists of a computational-theoretical study complemented by the experimental research. The experimental model consists of a metal sample vibrating at high frequency in liquid LBE. The low pressure area formed under the test sample surface leads to the appearance of cavitation bubbles. Changes in the oscillation frequency of the test sample and the pressure in the gas plenum of the test pot affect the cavitation. The occurrence of cavitation is determined by erosive wear of the sample surface and by the characteristic noise determined by an acoustic sensor. The influence of impurities contained in LBE and preconditioning of the sample surface is also investigated. In the computational part of the thesis, a cavitation model will be used to perform computational fluid dynamics (CFD) simulations of the test setup. The parameters in the cavitation model can then be adjusted to match the results obtained in the experiments.