Vibro-acoustique des structures immergées sous écoulement turbulent

Abstract : The aim of this thesis is the study of the hydrodynamic self-noise under a SONAR dome from 10 Hz to a few kHz. For this purpose, three particular studies has to be considered : the modelling of the vibro-acoustic behaviour of immersed structures in heavy fluid, the implementation of the turbulent boundary layer (TBL) excitation in deterministic formulations and the measurement of the response of a structure to a TBL. The first chapter is devoted to a bibliographical study of existing methods to deal with such problems. In the second chapter, we introduce the PTF (Patch Transfer Functions) method, which is based on substructuring and impedance/mobility concepts. This approach allows solving vibro-acoustic problems in the low and mid-frequency ranges. Because this method has only been applied to light fluid cases, one of the main issues of this chapter is the study of its applicability to heavy fluid cases. In the latter situation, convergence difficulties are observed. To overcome them, two strategies are developed in the third chapter to improve the global convergence of the method. The fourth chapter presents an application of the PTF method to a structure subjected to a TBL excitation and coupled to an external fluid medium and an acoustic cavity, cluttered up by elastic structures. To solve this problem, we first complete the PTF model by introducing the TBL excitation in the method from a plane waves expansion of the TBL cross-spectrum. Then, we introduce the computation of the PTF of an external fluid medium and that of a cavity cluttered up by elastic structures from a simplified model of the clutter. This application highlights the non-negligible influence of the clutter on the vibro-acoustic response of the whole system. In the fifth chapter, an experimental technique to simulate the behaviour of structures under TBL is developed. This technique is based on the plane waves expansion presented in chapter 4 and required the generation of wall pressure fields corresponding to those of propagating and evanescent waves to represent the spectral features of the TBL. To this end, a monopole array is used. The main parameters of the array are numerically estimated. The number of monopoles increasing with frequency, the experimental implementation of this technique can be delicate. To overcome this difficulty, the use of a synthetic antenna is introduced. The experimental validation of this technique is studied in the last chapter.
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  • HAL Id : tel-00777773, version 1

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Mathieu Aucejo. Vibro-acoustique des structures immergées sous écoulement turbulent. Acoustique [physics.class-ph]. INSA de Lyon, 2010. Français. ⟨tel-00777773⟩

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