Analyse numérique qualitative d'interactions rotor/stator dans un compresseur haute pression d'un moteur d'hélicoptère

In experimentalandnumericalinvestigationsofunilateralcontactandfrictioninducedrotorcasinginteractions,avarietyofcomplexphenomenaisexpected. Althoughmostofthefeatures of the structural responses can be explained within a simplifying linear framework, the nonlinear nature of contact and friction forces induce complicated responses which require an appropriate methodology to be conveniently analyzed. The presented work focuses on a thorough numerical exploration of such undesired events in an attempt to provide a dedicated systematic method of analysis. Interaction simulations are carried out on the centrifugal compressor of a modern helicopter engine, for which it is assumed that the casing is rigidly distorted along a mathematical shape exhibiting distinct nodal diameters. The proposed work focuses on linear geometric aspects, such as cyclic symmetry and spatial aliasing of engine orders on nodal diameters as well as nonlinear attributes, such as sub- and super-harmonic participations in the response, in order to properly characterize the dynamics of the interaction. The results are presented as space and time two-dimensional Fourier transforms of the numerically predicted response. Dominant responses are visible along time harmonics of the forcing frequency imposed by the assumed shape of the casing. It is observed that the participationof some nodal diametersin theresponseis a consequenceofboth the aliasingeffect and super-harmonic forcing terms.

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