Numéro : 1922 - Year : 1983
The low frequency behaviour of an immersed structure at a standstill in a high density fluid with free surface
A. LAURENT, Ingénieur Office National d'études et de Recherches Aérospatiales
At low frequencies, the mechanical behaviour of an immersed axisymmetric shell at a standstill, in a high density fluid with free surface entails a study of fluid/structure interaction and the air/fluid interface.
The Dynamics of the shell, prior to coupling with the fluid, can be described by the modal method which defines an eigen vector base that we shall call .'dry". Calculated with a collocation method, the NEUMAN problem yields resonances of the mechanical system to witch correspond a shell's deform, a damping ratio and a directional radiation.
In comparison to an infinite medium, the free surface has an effect on the pressure levels and the shape of the directional pressure radiation.
As means of identifying an immersed structure, we purpose correlating the displacements of the shell with the corresponding directional pressure radiation. This method has been applied to an axisymmetric ring-striffened structure with non-axisymmetric mass and stiffness perturbations. To conclude, attention should be brought to the importance of achieving a very fine modelling of the structure.
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