• vibrations
• Cast3M
• SFR
• hexagonal
• FSI
• Phénix
• Euler equations

The work focuses on the fluid flow three-dimensional effects during bidimensional
oscillation in narrow gaps, as the Phénix core or a SFR core.
For investigating this particular behavior two different approaches are used:
an experimental approach and a numerical one.
The numerical approach used for evaluating the edge effects is an analysis
with the Cast3M "upphi" code. The "upphi" model utilizes the Euler linearized
equation coupled with the spring-mass dynamic equation. This model is
used for representing the experimental facility PISE-1a, in order to analyze
the three dimensional behavior and the effects on the oscillating structure.
The experimental approach lies on the exploitation of two experimental
facility developed and manufactured by the cea of Saclay: the test-rig
PISE-1a and the small test facility PISE-2c, a hexagonal mono-assembly facility
and a two crowns of hexagonal assemblies respectively. The aim of the
design of those experimental facility is to reproduce the inertial effects of
the Phénix core assemblies. The three dimensional fluid flow (called “jambages”)
establishes itself in the inter assemblage space. This fluid behavior
is confirmed by some piv visualitation on PISE-1a. The effects on the structure
is a lower frequency vibration respect to the frequency evaluated by the
analytical bi-dimensional models.
Another part of the work concerns the setup of the small scale test
facility PISE-2c with the calibration and the characterization of its elements
for starting the new experimental campaign.
The present thesis work has been carried out during an internship at the
CEA of Saclay (Paris, France).