Identification of Pedestal Parameters in Rotor-Bearing-Pedestal Systems Using Known Unbalance

Abstract

Abstract This paper details a new technique for identifying the pedestal/foundation vibration parameters, viz. the pedestal or foundation stiffness, damping and mass matrices, of rotor-bearing-pedestal systems. Earlier approaches which relied on a knowledge of the hydrodynamic bearing forces as calculated from Reynolds equation, though promising in theory, proved unsatisfactory in practice. With this new approach on the other hand, at the expense of an additional run to enable the unbalance excitation to be correctly determined and assuming a knowledge of the rotor model, the uncertainties associated with bearing models are bypassed completely. It is shown both numerically and experimentally, that provided corresponding data are sampled at the same speed, good identification of pedestal parameters can be achieved even for pedestals supporting non-linear hydrodynamic bearings.