This Ph.D. project is part of an international research collaboration involving Siemens Energy, Safran group, and the Laboratory of Acoustics and Vibration Analysis in Polytechnique Montréal. This research is funded by a NSERC Alliance research grant and will involve at least 10 graduate students in total.

Context and objectives

More stringent environmental constraints and a very competitive global context force manufacturers to face new challenges in order to improve the efficiency of turbomachines, be it in the aerospace sector or for power generation. The impossibility to compromise safety or the environmental footprint of such systems means that in early design stages designers must now understand and account for nonlinear vibration phenomena - such as blade/casing contacts - that are still only partially characterized today. The proposed Ph.D. project is part of a larger research program that aims at developing a numerical strategy for the simulation, the characterization and the consideration of blade/casing contact phenomena within compressor blade design stages using two complementary solution paradigms: in the time domain and in the frequency domain. This research program will give the opportunity to both industrial partners to share their common knowledge and expertise on this topic in order to develop a uniform numerical tool suited both for gas turbines blades and aircraft engine blades.

The proposed research has three main objectives:

1. obj 1: Hyper reduction techniques for geometrically nonlinear reduced-order models. The inclusion of geometric nonlinearities in reduced-order models yields a significant computational burden that may lead to weeks of computations for the reduced-order model alone. Hyper reduction techniques offer a promising avenue for reducing computational times. The sub-objectives are: (a) implementation of existing methodologies to account for geometrical nonlinearities on a simplified blade model, (b) implementation and verification of hyper reduction techniques, and (c) industrial implementation on full 3D finite element models of blades and bladed disks.
2. obj 2: Development of thermo-mechanical mistuned bladed disk models. The combination of mistuning and contact non-linearities is a very recent field of research. Preliminary results indicate that localization factors tend to be significantly increased in comparison to those simulated in a linear framework. For blades where the vibration energy may be localized, thermo-mechanical effects may become essential to account for. The sub-objectives are: (a) development of the first mistuned thermo-mechanical models of bladed disks, and (b) targeted campaigns of numerical simulations to better understand the influence of localized vibrations on thermo-mechanical effects and specific wear phenomena.
3. obj 3: Implementation of a dynamic update of modal reduction bases] for efficient multiphysics nonlinear dynamics simulations.

Work environment

The selected candidate will be part of the LAVA which currently employ several researchers and graduate students working in areas closely related to that of the proposed research. All numerical developments will be made using the Python programming language. The candidate will benefit from the digital research infrastructure at LAVA (wiki website, gitlab platform, data and computation servers). The candidate will have the opportunity to supervise undergraduate students throughout the duration of the project.