The current work regards the sloshing in MYRRHA reactor under development at SCK-CEN. Sloshing is the oscillation of a liquid with a free surface. In the case of MYRRHA the sloshing caused by an earthquake is investigated. The software Ansys has been used for the simulations. During a seismic event the sloshing, in particular for heavy metal cooled reactors, can result in overloads for the structure, especially in case of resonance. The thesis develops a Fluid Structure Interaction procedure, for the coupling between a structural and a fluid field. The theoretical aspects precede the simulations. The modelling of fluids is first dealt with: models for turbulence, ow near walls and multiphase ow are presented. As a second step, the discussion moves towards the finite elements used for the structural aspects. The Fluid Structure Interaction coupling can be performed both by a 1 way and a 2 way approach: the second is required when the deformation of the structures has a significant impact on the velocity and pressure fields in the fluid. The many issues concerning FSI modelling for sloshing are also presented. The conclusion of the thesis suggests to move towards a modelling approach involving added masses and dashpots instead of the use of CFD in the case of the MYRRHA reactor. The large stiness of the components leads to structural resonance frequencies which are above the principal natural sloshing frequencies and the typical frequency spectrum of earthquakes.
|State||Published - 28 Jun 2016|