Simultaneous Estimation of Speed–Dependent Dynamic Parameters and Residual Unbalances in Rotor–Bearing–Coupling Systems

Abstract

The turbo-generator systems consist of driver and driven shaft performs significant role in power transmissions industries. A small amount of abnormality/fault present in these machineries lead to catastrophic failure of critical components (e.g., bearing, coupling, shaft, gearbox etc.) The catastrophic failure of these critical component results huge economic loss sometimes even worse loss of human life to the firm. In the past, practitioners of rotor dynamics have modelled coupling as having speed independent stiffness and damping parameters that lead to modelling error, due to the fact that the amount of misalignment depends upon different modes of excitation. That results speed dependency in stiffness and damping coefficients.
First, an identification algorithm has been developed for simultaneous estimation of the speed dependent bearing and coupling dynamic parameters along with speed independent residual unbalances, for rigid rotor, flexible bearing and coupling system. An analytical approach i.e., Lagrange’s equation is used to derive the system’s equations of motion (EOMs) in generalized coordinates and least squares technique is implemented to develop identification algorithm. The novelty of the present identification algorithm is the estimation of speed dependent coupling dynamic parameters along with speed dependent bearing dynamic parameters.
Next, the developed algorithm is extended for flexible rotor-bearing-coupling system and finite element method (FEM) is used to obtain systems EOMs. Flexible shafts are modeled with Timoshenko beam theory and standard eight linearized stiffness and damping coefficients are used to model bearing and coupling.
To check the robustness of the identification algorithm, measurement noise has been added in numerically simulated response. Well agreement in the estimated parameters is observed for a different level of measurement noise.