Thèse Contrôle de la Propagation des Ondes Vibro-Acoustiques dans les Tuyaux à Partir de Tours Noirs Acoustiques H/F

Doctorat.Gouv.Fr

Établissement : INSA Lyon
École doctorale : MEGA - Mécanique, Énergétique, Génie Civil, Acoustique
Laboratoire de recherche : LVA - Laboratoire Vibrations Acoustique
Direction de la thèse : Laurent MAXIT ORCID 000000018671903X
Début de la thèse : 2026-10-01
Date limite de candidature : 2026-05-01T23:59:59

The propagation of noise and vibrations in hydraulic systems is a critical issue across numerous industrial sectors, including building services, energy, and aerospace. Noise sources are primarily linked to hydraulic pumps generating pressure pulsations in the circuit. Structural vibrations can lead to mechanical fatigue, particularly at pipe junctions, with potentially serious consequences for the operation and safety of hydraulic installations. Furthermore, acoustic waves propagating inside the pipe can be a source of noise disturbance, especially in building-related applications. Developing effective devices to control the propagation of vibrations and acoustic waves in pipes is therefore of primary importance.
The Acoustic Black Hole (ABH) concept [1] appears as a promising approach in this context. It has been investigated in laboratory settings by various research groups over the past decade. Through specific geometric design, the ABH aims to slow down wave propagation and concentrate energy in a specific zone where it can be dissipated as heat through thermoviscous or viscoelastic effects. Two main types of ABH exist:
- Structural ABHs slow down the propagation speed of flexural waves by reducing the thickness of a structure according to a power-law profile, with a viscoelastic element added at the tip to promote energy dissipation.
- Sonic ABHs [4, 5] slow down acoustic wave propagation using a system of concentric rings with progressively smaller apertures; absorbing materials at the termination or micro-perforated panels are used to enhance thermoviscous losses.
While existing literature on ABHs largely focuses on applications in air - including sonic black holes in air-filled ducts [2, 3] and structural ABHs embedded in beams, plates and shells [4, 5] for vibration damping - the case of hydraulic piping introduces an important additional complexity: a strong fluid-structure coupling between the elastic pipe wall and the heavy internal fluid [6]. Depending on the frequency range and the circumferential modes involved, vibroacoustic energy can be distributed between structural and acoustic medium in ways that differ fundamentally from the light-fluid case.
In this context, this thesis proposes to study the impact on vibroacoustic wave propagation of ABH devices mounted on a heavy fluid-loaded pipe. The work will consider structural ABHs attached to the outer surface of the pipe and/or sonic ABHs inserted between two pipe sections.
The research programme is defined as follows:
-realization of a bibliographic review;
-familiarisation with simple models of structural and sonic ABHs;
-development of an analytical model of a fluid-filled cylindrical shell and analysis of propagation modes in function of the frequency range;
-selection of one ABH concept for the following of the study;
-development of numerical vibroacoustic models representing the ABHs coupled to heavy-fluid-filled cylindrical shells (fully finite element models (FEM) or/and hybrid finite element /analytical models);
-parametric analysis of ABH performances on the vibroacoustic propagation as a function of frequency range and circumferential modes;
-experimental validation on a test case in a laboratory (during the 6 months secondment in Grundfos, a pump manufacturer);
-writing of the thesis manuscript.

The propagation of noise and vibrations in hydraulic systems is a critical issue across numerous industrial sectors, including building services, energy, and aerospace. Noise sources are primarily linked to hydraulic pumps generating pressure pulsations in the circuit. Structural vibrations can lead to mechanical fatigue, particularly at pipe junctions, with potentially serious consequences for the operation and safety of hydraulic installations. Furthermore, acoustic waves propagating inside the pipe can be a source of noise disturbance, especially in building-related applications. Developing effective devices to control the propagation of vibrations and acoustic waves in pipes is therefore of primary importance.
The Acoustic Black Hole (ABH) concept [1] appears as a promising approach in this context. It has been investigated in laboratory settings by various research groups over the past decade. Through specific geometric design, the ABH aims to slow down wave propagation and concentrate energy in a specific zone where it can be dissipated as heat through thermoviscous or viscoelastic effects. Two main types of ABH exist:
- Structural ABHs slow down the propagation speed of flexural waves by reducing the thickness of a structure according to a power-law profile, with a viscoelastic element added at the tip to promote energy dissipation.
- Sonic ABHs [4, 5] slow down acoustic wave propagation using a system of concentric rings with progressively smaller apertures; absorbing materials at the termination or micro-perforated panels are used to enhance thermoviscous losses.
While existing literature on ABHs largely focuses on applications in air - including sonic black holes in air-filled ducts [2, 3] and structural ABHs embedded in beams, plates and shells [4, 5] for vibration damping - the case of hydraulic piping introduces an important additional complexity: a strong fluid-structure coupling between the elastic pipe wall and the heavy internal fluid [6]. Depending on the frequency range and the circumferential modes involved, vibroacoustic energy can be distributed between structural and acoustic medium in ways that differ fundamentally from the light-fluid case.

The research programme is defined as follows:
-realization of a bibliographic review;
-familiarisation with simple models of structural and sonic ABHs;
-development of an analytical model of a fluid-filled cylindrical shell and analysis of propagation modes in function of the frequency range;
-selection of one ABH concept for the following of the study;
-development of numerical vibroacoustic models representing the ABHs coupled to heavy-fluid-filled cylindrical shells (fully finite element models (FEM) or/and hybrid finite element /analytical models);
-parametric analysis of ABH performances on the vibroacoustic propagation as a function of frequency range and circumferential modes;
-experimental validation on a test case in a laboratory (during the 6 months secondment in Grundfos, a pump manufacturer);
-writing of the thesis manuscript.