Snecma Moteurs

Marc Berthillier

Jacky S Naudet

Yvon Cloarec

Eric Seinturier

Jean-Luc Mary

Andr&eacute; Collot

Andre Collot

A method of reducing vibration in a structure comprising at least one rotor () and a fixed set of sources of disturbance () liable to give rise to disturbances in the fluid flow () that cause the rotor to vibrate, the method comprising a step of distributing the fixed sources of disturbance angularly in non-uniform manner so as to reduce the amplitude of excitation as seen by the rotor, and a step which consists in verifying that the maximum amplitude of a response of the rotor to the excitation is obtained by:

Structure comprising a rotor and fixed perturbation sources and method for reducing vibrations in said structure

These objects are achieved by a method of acoustically inspecting a one-piece bladed wheel in which the wheel is driven in rotation; each blade of the wheel is subjected to mechanical excitation; its acoustic response is picked up and a corresponding electrical signal is generated; its frequency response is determined by computing a FFT; the electrical signal and the associated frequency response are stored; the characteristic frequencies of each blade of the wheel are identified; and a wheel is rejected or accepted depending on whether or not the frequency distribution obtained in this way matches a predetermined set of forbidden frequency distributions. Advantageously, an additional step is provided in which the defects of a blade are determined by comparing its frequency response with predetermined frequency responses that are characteristic of various types of defect.

Acoustic inspection of one-piece bladed wheels

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Yerres, France

Marc Berthillier