Session: 28-05: Mistuning of bladed disks

Paper Number: 151617

Implementation of Intentional Mistuning by Means of Finite Element Based Shape Optimization 

Intentional Mistuning has turned out to be an effective measure to alleviate the maximum forced response of bladed wheels in the framework of numerous studies in the past. In particular solutions based on two different blade designs, following e.g. alternating or AABB patterns, have proved to be promising in this regard and moreover robust against the impact of unavoidable random mistuning. Thus, for example, a 40 percent reduction of the first blade bending maximum forced response has been proved experimentally for a turbine impeller of a turbo charger application [1]. Despite this success, the technical implementation of the frequency based mistuning pattern followed an academic solution based on locally removing material at the leading edge tip, which is not suited for the use in serial wheels since it may disturb the flow channel. In addition, the forced response of other blade modes may be affected in a negative manner. In order to overcome these problems, an alternative way of implementing Intentional Mistuning is suggested by applying a marginal geometric modification of the blade thickness distribution to adjust the natural frequency of the first bending mode. Finite element based shape optimization is utilized to this end. Secondary conditions are ensuring that only the target frequency of the first bending mode is adjusted whereas natural frequencies of other modes are kept almost unchanged.

[1] Nakos, A., Beirow, B., Wirsum, M., Schafferus, M., Sasakaros, M., Vogt, D., Zobel, A.: "Mistuning and Damping of a Radial Turbine Wheel. Part 3: Validation of Intentional Mistuning During Machine Operation". ASME Paper Number: GT2023-101993, Boston, Massachusetts, June 26-30, 2023. https://doi.org/10.1115/GT2023-101993.

Presenting Author: Bernd Beirow Brandenburg University of Technology

Presenting Author Biography: 1987-1993: Studies of aeronautical engineering at the Technical University of Berlin
1994-2000: Research assistant at the BTU Cottbus, Chair of statics and dynamics (Faculty of civil engineering)
2000: PhD at BTU Cottbus (Subject: ’Experimental and theoretical investigations of the vibration behaviour of transmission towers’)
2001: Lecturer and senior research assistant at BTU Cottbus, Chair of structural mechanics and vehicle vibrational technology
2009: Habilitation
Since 2020: Professor at BTU Cottbus, Chair of structural mechanics and vehicle vibrational technology

Authors:

Bernd Beirow Brandenburg University of Technology
Alex Nakos Brandenburg University of Technology
Caroline Stecklina Brandenburg University of Technology
Martin Noack FEMopt Studios GmbH
Matthias Firl FEMopt Studios GmbH
Sasakaros Marios RWTH Aachen University