Patent ID: 6415206
Filing Date: 2002-07-02
Classification: B64C,G05D

Abstract:
A method of determining a minimal set of rotor blade adjustments for a rotor to which a plurality of rotating blades are attached, said rotor being supported by a supporting structure, said set of adjustments for reducing supporting structure vibration over at least one harmonic order of rotor rotation, said method comprising the steps of:providing measurements of vibration at predetermined locations on said supporting structure; resolving said vibration measurements into a corresponding set of Fourier coefficients of vibration for at least one of said locations, each Fourier coefficient of vibration of said set corresponding to a harmonic order of rotor rotation; establishing a vibration model of said supporting structure comprising Fourier coefficients of unit vibration influence for said at least one location, said Fourier coefficients of unit vibration influence corresponding to harmonic orders of rotor rotation; establishing a set of Fourier coefficients of adjustment for at least one blade adjustment type, said set of Fourier coefficients of adjustment corresponding to a set of blade adjustments associated with each blade adjustment type, said Fourier coefficients of adjustment corresponding to harmonic orders of rotor rotation; selecting at least one Fourier coefficient of adjustment from each blade adjustment type set; establishing a relationship by which vibration of said supporting structure may be calculated at harmonic orders of rotor rotation from said Fourier coefficients of adjustment, said Fourier coefficients of unit vibration influence and said Fourier coefficients of vibration measurements; determining a value of each selected Fourier coefficient of adjustment that provides a desired virtual reduction of vibration of said supporting structure at at harmonic order of each selected Fourier coefficient of adjustment using said vibration relationship; determining a group of minimal sets of virtual blade adjustments for each type based on said determined value of each selected Fourier coefficient of adjustment; and determining a minimal set of virtual blade adjustments from said group of each type based on its affect on the vibration relationship at at least one harmonic order of rotor rotation other than said harmonic order of each selected Fourier coefficient of adjustment.