Software & Development Tools
As the blades deployed in turbomachines are subjected to high mechanical and thermal loads, these components must be manufactured with great precision. Despite this, small defects can occur, which become apparent during operation through disruptive vibration phenomena. This “mistuning” can have a negative impact on the acoustic behaviour and service life of the machine. Therefore, FVV initiated the first project on mistuning in 1993 and has since conducted numerous projects, thereby helping to bring this phenomenon under control from a technical perspective. One open question was how the blades in a blade ring influence one another via the fluid flowing through – in combination with non-linear coupling via frictional contact. Vibration and turbomachine experts from Leibniz University in Hanover collaborated to analyse the vibrations caused by the coupling of aerodynamics and structural mechanics in the “Mistuning with Aerodynamic Coupling I/II” project.
» Research on the phenomenon of mistuning is helping to improve our understanding of the resonance passages in turbomachine impellers, and thus contributing to operating safety. «
Rotor discs in the compressor with integrated blades, called blisks, make engines lighter, more powerful and more economical
Installing the rotor discs on the test bench
Efficient turbomachines are playing a key part in the transition to greener energies. In order to guarantee safe operation despite mistuning, the blades, or blisks (blade-integrated disks) were previously designed with greater material thicknesses than would have been necessary based on the residual operating loads. However, this hinders efforts to further increase turbomachine efficiency. An ideal aerodynamic design is only possible if the mistuning effects that occur during operation can be calculated at an early stage of development.
» Our goal is to use experimental validation to make the ROMI simulation software – which was developed within the scope of FVV projects – ever more accurate. «
The empirical basis for the further development of the simulation software was created via experiments performed at the involved institutes at the Leibniz University in Hanover. At the Institute of Dynamics and Vibration Research (IDS), an idealised turbine stage was agitated via magnetism in a vacuum in order to determine structural-mechanical couplings. On a test bench at the Institute of Turbomachinery and Fluid Dynamics (TFD), experiments were performed with a fluid flowing through, while taking the damping effect of the fluid into account. The findings gained through these experiments were then used to revise the modelling of the mistuning effect.
The FVV project, which was completed at the end of 2019, significantly improved the existing ROMI (Reduced Order Model for Mistuned Turbine Blades) simulation program. By coupling the aerodynamics with the structural dynamics of the shroud or blade root, the increase in vibration amplitudes can now be predicted more accurately. The results also show that vibration behaviour is largely influenced by the relative movements of the blade roots in the mounting slots. ROMI is a non-commercial tool which can be used both in subsequent research projects and in the development of highly efficient turbomachines.
Mistuning with Aerodynamic Coupling | Mistuning of bladings with aerodynamical and structural couplings | Funding No. 1164
Mistuning with Aerodynamic Coupling II | Mistuning of bladings with aerodynamical and structural couplings | Funding No. 1269
Public & FVV Funding
2014-03-31 to 2016-12-30 Part I
2017-06-30 to 2019-12-30 Part II
Dr.-Ing. Harald Schönenborn
MTU Aero Engines AG
1 | Institute of Dynamics and Vibration Research (IDS) - Leibniz Universität Hannover | I + II
Head of research:
Prof. Dr.-Ing. Jörg Wallaschek
2 | Institute of Turbomachinery and Fluid Dynamics (TFD) - Leibniz Universität Hannover | I + II
Head of research:
Prof. Dr.-Ing. Jörg Seume
Research Association for Combustion Engines eV
Lyoner Strasse 18
60528 Frankfurt am Main
T +49 69 6603 1345