Work Description

Through these 3 test-beds, the PHARE experimental facility will lay out a bold and comprehensive research project. This scientific endeavor can be broken down into 3 main topics:

T1 : Structural instabilities linked to failure and contact processes

This scientific topic will primarily be exposed via test-bed 1. The program adopted has been divided into two highly complementary fields of activity. The first focuses on both linear and nonlinear stationary vibration phenomena, while the second is devoted to fast and transient dynamic aspects.

T2 : Aerodynamic and aeroelastic instabilities, along with aeroacoustic signatures

This topic is intended to study instabilities in relation to the presence of fluid, which requires a `multi-physical` and `multi-scale` approach, wherein the coupling of physical parameters (aerodynamics, mechanics and acoustics) plays a pivotal role.
This research effort is directly correlated with test-bed 2 and centered on three scientific subtopics: aerodynamic instabilities, aeroelastic instabilities, and aeroacoustic signatures. While a body of work can be found in each of these three areas on low-speed machines, studies on their couplings in realistic machines are practically nonexistent. The objective behind the PHARE project is to successfully quantify this coupling, by concentrating on:

  • the link between forced vibrations in asynchronous situations and behavior of outer layers in the vicinity of aerodynamic instability;
  • the link between certain acoustic mechanisms like upstream/downstream `cut-off/cut-on` modes and the initiation of flutter.

T3 : Structural instabilities related to external loadings

The set of research conducted by LaMCoS in the field of rotating machine dynamics focuses on line shafting and rotating assemblies. The approach consists of predicting the dynamic behavior in stationary and transient states while remaining capable of controlling their stability mainly by means of passive and active channels. Building the most relevant and reliable models possible requires taking into account, and increasingly cumulating, the effects of nonlinearities, couplings and uncertainties, along with the deterministic or non-deterministic loadings that, introduced by the database, are responsible for generating parametric excitations. The development of new monitoring and diagnostic techniques complements this body of research.
Over the past few years, LaMCoS has extended its research and specialty technologies, including hybrid bearings, based on electromagnetic actuation, self-adaptive balancing and high-precision measurement of rotating speeds, so as to better face the upcoming technological and scientific challenges introduced due to increasingly compact machines that incorporate higher intelligence, along the lines of smart machines. Excitation test-bed 3 with 6 degrees of freedom placed in a climatic environment will help broaden the field of investigation for current research by expanding the observation and analysis of measured phenomena and by emphasizing experimental validation of the models developed.