Application of Reduced-order Aerodynamic Modeling to the Analysis of Structural Uncertainty in Bladed Disks

Blade-to-blade variations can significantly impact the operation of bladed disks. In this paper, a method is presented for assessing the effects of these variations using a high-fidelity aerodynamic analysis. Systematic model reduction is applied to a high-order computational fluid dynamics code using the proper orthogonal decomposition technique. This results in a low-order model suitable for time domain computations of mistuning effects. The model is shown to capture the dynamics of the aeroelastic system more accurately than with a traditional influence coefficient approach. Results are presented for a bladed disk with structural uncertainty, where the blade frequencies exhibit random variations about a nominal state. Finally, the concept of a robust design is explored, in which intentional variation is introduced to the system in an attempt to alleviate the ill-effects of random variations. The approach can also be extended to consider aerodynamic uncertainty, which may arise from geometric variations.