Method for determining a minimal set of rotor blade adjustments

A method for determining a minimal set of adjustments for the blades of a rotor supported by a supporting structure for reducing rotation-induced vibration in the supporting structure at at least one harmonic rotation order and/or for reducing track deviation while maintaining structure vibration over at least one harmonic order within an acceptable limit. In one embodiment, a relationship is established by which vibration of the supporting structure may be calculated at harmonic orders of rotor rotation from Fourier coefficients of adjustment, Fourier coefficients of unit vibration influence and Fourier coefficients of vibration measurements. Thereafter, a value is determined for each selected Fourier coefficient of adjustment that provides a desired virtual reduction of vibration of the supporting structure at the harmonic order of the selected Fourier coefficient of adjustment using the vibration relationship. A group of minimal sets of virtual blade adjustments are determined for each type based on the determined value of the corresponding selected Fourier coefficient of adjustment, and from the group, a minimal set of virtual blade adjustments of each type is determined based on its affect on the vibration relationship at at least one harmonic order of rotor rotation other than the harmonic order of the selected Fourier coefficient of adjustment. In another embodiment, track measurements are provided that are resolved into corresponding Fourier coefficients of track that are used to establish a relationship by which track of the rotating blades may be calculated. Thereafter, a value is determined for each selected Fourier coefficient of adjustment that provides a desired reduction of track deviation using the track relationship. A group of minimal sets of virtual blade adjustments is determined based on the determined values, and from the group, a minimal set of virtual blade adjustments is determined based on its affect on the vibration relationship.