Mistuning Identification for Rotating Bladed Disks Using Stationary Measurements and Reduced Order Models

Abstract

Abstract Although full-scale representative experiments provide critical data for final validation of designs, there is increasing emphasis on computational and reduced scale experiments to test out initial design concepts. This is true in many fields, especially in the field of turbomachinery; turbomachines are complex machines that operate at high temperatures and pressures for long durations of time and it is very expensive to build prototypes and conduct full scale testing. Stationary test rigs are cheaper to design and operate than rotating test rigs, but can lack the proper boundary conditions required to mimic actual operating conditions. A key characteristic of the design that is identified from experiments for bladed disks is mistuning. Mistuning are the sector to sector differences in bladed disks due to manufacturing tolerance, operational wear, or material deviations, and can lead to vibration localization. This work provides insight in correlating stationary mistuning measurements to the mistuning observed in a rotating bladed disk. The mistuning values from bench-top tests are shown to match the mistuning values from the rotating experiments. A parametric reduced order model (PROM) is constructed using stationary mistuning values to model the fully mistuned system, complete with rotational speed effects such as stress stiffening. The PROM enables changing the mistuning and rotational speed effects in the reduced space. The natural frequencies of the computational model are compared to the experimental blade frequencies to show that the computational model is similar to the experimental system. The final model can then be used to simulate the physical experiments using time integration methods.