A novel modal vibration reduction of a disk-blades of a turbine using nonlinear energy sinks on the disk

Abstract

This study evaluates the application of nonlinear energy sinks (NESs), mounted on the disk of a real packeted bladed disk, for an indirect passive vibration attenuation of blades. To this end, the finite element analysis is used to extract the natural modes and SAFE diagram. The cyclic symmetry property reduces the size of the system to the degrees of freedom (DOFs) in a sector containing only one packet and a disk slice. In addition, a 2-DOF reduced order model (ROM) is obtained for the two first modes of the bladed disk. The NES with an essential nonlinear stiffness and a linear damping is added to this ROM to suppress the blades vibration. Then, theoretical and numerical analyses are followed by employing the perturbation and Runge-Kutta methods to solve the system motion equations. Finally, the occurrence of Saddle-Node (SN) and Hopf bifurcations and responses like periodic and strongly modulated responses are surveyed. The results demonstrate a good performance of NESs at the second nodal diameter (ND) of the first mode due to a strong coupling between blades and the disk in out-of-plane modes and a poor performance at the second mode due to a weak coupling in in-plane ones.