Fluid-structural coupling effects on the dynamics of mistuned bladed disks

Mistuning changes the vibration of bladed disks dramatically. Various aeroelastic models have been used to investigate the free vibration and forced response problems of mistuned bladed disks. Most of these models used simplified structural and/or aerodynamic models. The traditional way to incorporate the aerodynamic coupling in the high-fidelity structural models is to use the cantilever-blade normal modes to calculate the unsteady aerodynamic forces. In this paper, a new reduced-order modeling approach is developed by using the tuned system modes to calculate the unsteady aerodynamic forces directly. This new approach is applied to an industrial rotor. The results show that aerodynamic coupling has significant effects on the vibration of bladed disks for the case studied. Also, constraint modes are needed to yield accurate results if cantilever-blade normal modes are used to calculate the unsteady aerodynamic forces. However, using the tuned system modes to calculate the unsteady aerodynamic forces saves a significant amount of computation time compared to the method using both cantilever-blade normal modes and constraint modes.