Centrale LYON - Doctorat Dynamique Non-Linéaire des blisks Désaccordés en Présence D’effets de Coriolis

Job Title

The job title is not explicitly mentioned in the provided HTML. However, based on the context, it seems to be a research position related to the DyVA industrial chair at the École Centrale de Lyon.

The École Centrale de Lyon, established in 1857, is among the top 10 engineering schools in France. It educates over 3,000 students from 50 different nationalities across its campuses in Écully and Saint-Étienne (ENISE, an internal school). The school offers programs for generalist and specialist engineers, masters, and doctoral students. With the Centrale School Group, it has three international campuses. The education provided benefits from the excellence of research conducted by the 6 CNRS-labeled laboratories on its campuses, the 2 international laboratories, the 6 international research networks, and the 10 joint laboratories with companies.

Its research excellence and high-level teaching enable it to establish double-degree agreements with prestigious universities and cutting-edge partnerships with numerous companies. Focusing on themes of sobriety, energy, environment, and decarbonization, Centrale Lyon aims to address the challenges of socio-economic actors in major transitions.

In this context, the DyVA industrial chair, co-funded by the ANR and the SAFRAN group, aims to address environmental challenges in the aeronautics sector, involving a drastic reduction in CO2 emissions in the medium and long term with a low-carbon objective by 2035 and neutrality by 2050. Thus, on technological programs like RISE, launched by SAFRAN, it will be necessary to be able to accurately analyze the new operating points obtained and their impacts on engine dynamics and lifespan.

Indeed, this project addresses a large number of technologies that break with conventional architectures such as an open-fan, an open-OGV, and a fast turbine and booster.

The DyVA project thus fully fits into this context and aims to develop advanced numerical tools to address the issue of vibration prediction of new aeronautics motorizations. The developments envisaged will focus on the simulation and modeling of nonlinear dynamic behavior and uncertainties to offer a deep understanding of the underlying system dynamics and to master its physics, simulation, and the ensemble of different possible operating points.

These results will be correlated with experimental tests, thus providing measurements often not present in the literature but essential for a good understanding of the physics.

This research work is dedicated to the experimentation and development of numerical models of a monobloc high-pressure compressor blade. The thesis will focus on the analysis of nonlinear combined dynamics, detuning, and gyroscopic effects. The objective is to master the design of these new designs and the opportunities they offer in terms of energy efficiency.

The studied specimen (blade) will exhibit detuning, Coriolis effects, and friction interfaces with a friction joint. This research work will be divided into two axes:

Nonlinear Damping by Split-Ring Damper - The blisks have very low structural damping. Manufacturers then add dissipation using friction joints. However, the system's actual efficiency, which depends on several physical factors, shows that it is necessary to progress in design [2]. In [1], the harmonic response of the nonlinear dynamic system is derived using the Lagrangian frequency-time method adapted to cyclic structures.

It is shown that efficiency depends on blade/disk coupling, and slip/adhesion alternations. However, the Coriolis effect is not integrated although known for blisks.

Nonlinear damping will be estimated on a real specimen implemented in Phare-1 (figure
1). The vacuum estimation will be correlated with the solutions calculated by the harmonic balance method (HBM).

Coriolis Effect versus Detuning - The Coriolis effect must be taken into account in the analysis of the response to detuning. Indeed, detuning is favorable to the stabilization of flutter and is competitive with the Coriolis effect. The influence of these two phenomena has been studied numerically using a reduction method on a…