Annihilation of non-stationary vibration of a gas turbine rotor system under rub-impact effect using a nonlinear absorber

In this study, the effects of a smooth nonlinear energy sink (NES) on a continuously rotating system is investigated by considering its non-stationary motion and rub in disks positions. This rotary system is modeled based on a gas generation (GG) section of an industrial gas turbine. The contact between the rotor and stator is considered to be elastic with Coulomb-type frictional forces. It is considered that the NES's damping and stiffness are linear and cubic, respectively. The shaft is modeled using Rayleigh beam theory and the extended Hamilton principle is employed to obtain the equations of motion. In order to fully model the dynamics of the system, in the Galerkin method, the first three bending modes of the system are used. The genetic algorithm is used to obtain the optimized parameters of the NES and minimize the Root Mean Square (RMS) near to operating speed and the peak amplitudes of the rotor vibrations in the working range. It is demonstrated that the NES can considerably decrease the vibration level and possibility of rub phenomenon in the non-stationary motion of rotating system within a wide range of rotational speed and also can make the motion of the system smoother. (C) 2019 Elsevier Ltd. All rights reserved.