Abstract
Campbell diagrams are commonly used for designing rotating machinery to avoid resonance frequencies. Authors have proposed improved Campbell diagrams, of which the indication is modified to be more intuitive. A signal processing, which distinguishes between forced vibration and free vibration, has been applied to diagnosis of blade-shaft coupled vibration. In this paper, case studies of vibration diagnosis of rotating machinery using the improved Campbell diagrams are introduced: vibration of flexible rotor supported by active magnetic bearings, blade vibration of steam turbine-generator set, blade-shaft coupled resonance and abnormal blade vibrations of blade-shaft coupled system. For example, in the case of abnormal blade vibrations of blade-shaft coupled system, the improved Campbell diagram allows for detailed nonlinear analysis of entrainment phenomenon of forced self-excited system by separating it to forced vibration and self-excited vibration. Through these case studies, we report effectiveness of the use of our improved Campbell diagrams.
