Patent ID: 7029227
Filing Date: 2006-04-18
Classification: F01D,F04D,F16F

Abstract:
1. A method of reducing vibration in a structure including at least one rotor and at least one stator, the rotor and the stator configured to be subjected to a fluid flow, the structure including a set of fixed sources of disturbance liable to give rise to disturbances in the fluid flow that cause the rotor to vibrate, the method comprising: during design of the structure, selecting a non-uniform angular distribution for the fixed sources of disturbance to reduce the amplitude of excitation seen by the rotor and corresponding to said disturbances at at least one excitation frequency that coincides substantially with a natural frequency of the rotor at a speed of rotation V thereof, as compared with a predetermined uniform angular distribution of the fixed sources of disturbance; and verifying over an entire range of speeds of rotation at which the rotor is liable to rotate and including the speed of rotation V, that a maximum amplitude of a response of the rotor to the excitation when the fixed sources of disturbance are distributed in said selected angular distribution is less than a maximum amplitude when the fixed sources of disturbance are distributed in said predetermined angular distribution, said response of the rotor to the excitation when the fixed sources of disturbance are distributed in said selected angular distribution being obtained by: modifying the first signal into a second signal adapted to said selected angular distribution for the fixed sources of disturbance; determining the frequency spectrum of the excitation by calculating the Fourier transform of the second signal; and calculating the response of the rotor to the excitation based on the frequency spectrum of the excitation.