Nonlinear aeroelasticity and transient multiresonances

Due to regeneration processes and manufacturing tolerances, deviations occur on the turbine blades that can affect the vibration behavior of the stage. The resulting magnification of resonances has a significant impact on blade durability and structural integrity. In previous projects, funded by the DFG as part of the Collaborative Research Center 871, the influence of mistuning was calculated with RAMBO on a linear structure and validated with experimental data. Based on these studies, an almost real-world blading will be investigated, which is provided by an industry partner. Starting with a linear, tuned stage, the complexity of the model is successively increased to account for mistuning, transient resonance passages, multi-frequency excitations, nonlinear contacts, and aerodynamic damping. Furthermore, in contrast to previous projects of the Collaborative Research Center, the misalignment of the blades takes into account not only the structural mistuning, but also the mistuning of the linearized interblade contact areas. Experimental investigations under rotation by the Institute of Turbomachinery and Fluid Dynamics, as well as vibration tests at the Institute of Dynamics and Vibration Research, complete the data base for parametrization and allow the calculated vibrations to be evaluated.

To ensure the comparability of the results, a common data set for geometry, excitation and boundary conditions is used. The utilization of this data set has been tested for a simplified model in different calculation tools. The aerodynamic calculations are conducted in cooperation with the Institute of Turbomachinery and Fluid Dynamics, so that a common interface for data transfer has been defined and tested. The current research focus is the preparation of the application-oriented blade model for the usage in the abovementioned calculation tools.