Experimental and numerical investigations on rotor–stator rub

The focus of the current study is on the dynamics of rubbing between the rotor and stator parts in a rotating machine. Rub is a malfunction associated with the physical contact of rotating and stationary parts, which are otherwise not in contact. Because of the nonlinear nature of the problem the simulation time is significant even for small size systems. The rubbing is localized in space, either at the seal locations or at the interface between the rotor blade and stator. Since the nonlinearity is localized, reduced models can be developed for efficient computation. The objective of the present study is to develop a computationally efficient methodology for analyzing the rotor stator rub, by applying model reduction techniques using component mode synthesis, solving the reduced problem using harmonic balance method and time variational method. A hypersphere-based continuation algorithm is used for tracing the unstable branches and a backward differentiation formula based predictor is used for the Newton–Raphson update. The numerical results are validated by performing experiments.