Context and general objective :

The proposed PhD thesis is part of the work carried out on the SESAME loop, installed at the Fluid Mechanics Laboratory of Lille, on the Arts et Métiers campus in Lille. This facility enables water tests in cavitating conditions for space pump inducers. In addition to measuring inducer performance, the test equipment allows for dynamic measurements of pressures at the casing and efforts on the shaft. The test bench was recently equipped with a new transparent inlet pipe, enabling high-speed camera visualization of cavitation patterns.

Recent works (Eddy Terrasse PhD thesis, defense scheduled for March 2026) enabled the development of a series of tools (instability mapping, reconstruction of radial forces [1], image analysis) that improve the characterization and understanding of instabilities developing in this type of machine.
The aim of the present proposal is to extend the analyses previously conducted under classical conditions (purely axial inlet and no external excitation) to more complex cases, including spatial distortions of the flow feeding the machine and temporal excitations at imposed frequencies.

Subject :

The subject is set in the context of evolving engine architectures, where installing two pumps on the same shaft requires one of the machines to be fed radially. The impact of this type of supply on the development of cavitation instabilities and its effects on the efforts supported by the bearings is unknown and needs to be investigated, especially since it is known that, in other types of machines, such upstream distortion has significant effects on performance and internal flow behavior.
The SESAME loop, support of the work, has an inducer inlet pipe developed by ArianeGroup that allows radial feeding. The first objective of the thesis work will be:

•    to determine, through measurements under various operating conditions, the impact of the distortion level on the unsteady cavitation behavior in the machine,
•    to model, using simplified approaches, the impact of these distortions on the machine behavior to provide a predictive tool adapted to non-uniform feeding.

In this area, the work will benefit from the research team's experience on the effects of upstream distortion on the performance and stability of other types of rotating machines [2-3].

The second objective of this thesis is to experimentally evaluate how an external temporal excitation can interact with the natural modes induced by unstable cavitation regimes. This type of work is set in the applied context of the development of POGO-type instabilities, which can be destructive for launchers and occur when the pump's natural modes resonate with circuit and structural modes [4].

The work will first consist of designing an experimental device capable of generating controlled amplitude fluctuations over a range of low frequencies representative of the effects to be simulated. 

These fluctuations can be generated by a circuit composed of one or more flexible tubes connecting the upstream and downstream sides of the pump.

This device will be installed on the SESAME loop and its performance characterized.

A test campaign will then be conducted on an inducer. The analysis of experimental results (unsteady pressure sensors, force measurements, and visualization), particularly under cavitating conditions, will allow characterization of how the impact of external excitation affects the development of instabilities in the machine.

References:
[1] Estimate of the radial unsteady forces acting on a cavitating inducer from casing pressure measurements
E Terrasse, O Roussette, M Queguineur, H Staudt, A Dazin
IOP Conference Series: Earth and Environmental Science 1411 (1), 012037
[2] Scaling Laws at Stall in an Axial Compressor with an Upstream Perturbation
A Baretter, P Joseph, O Roussette, A Dazin, F Romanò
Journal of Propulsion and Power 41 (1), 82-98
[3] Experimental analysis of an axial compressor operating under flow distortion
A Baretter, P Joseph, O Roussette, F Romanó, A Dazin
Turbo Expo: Power for Land, Sea, and Air 86090, V10AT29A030
[4] Advanced Pogo stability analysis for liquid rockets
Bohdan W. Oppenheim and Sheldon Rubin
Journal of Spacecraft and Rockets 1993 30:3, 360-373

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For more Information about the topics and the co-financial partner (found by the lab!); contact Directeur de thèse - antoine.dazin@ensam.eu

Then, prepare a resume, a recent transcript and a reference letter from your M2 supervisor/ engineering school director and you will be ready to apply online  before March 13th, 2026 Midnight Paris time!