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Institute of Turbomachinery and Fluid Dynamics
Logo Leibniz Universität Hannover
Institute of Turbomachinery and Fluid Dynamics
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Acoustic Blade Excitation for Aeroelastic Studies

Field of Application

  • Non-contact blade excitation
  • Application in non-rotating and rotating turbomachinery test rigs
  • Experimental aeroelastic investigations

Excitation System

Developing improved prediction models is necessary to investigate aeroelastic phenomena in turbomachinery (e.g. forced response and flutter). However, experimental validation of these models is needed. For this, highly accurate experimental measurements of blade vibrations in rotating machines, which consider realistic machine-conditions, are necessary. The biggest challenge of experimental blade excitation investigation is the mistuning (altering of the modal properties and frequencies of the investigated blades) introduced to the systems by the excitation technique itself. To ensure realistic conditions, a well-defined contact-free excitation of the blades is mandatory. 

At the TFD, a non-contact acoustic blade excitation system for applications in non-rotating and rotating test rigs has been developed. Besides the major advantage of contact-free excitation, acoustic excitation allows a high degree of flexibility in the excitation frequency as well as in the intensity or amplitude of the excitation. Moreover, it is possible to excite definite mode shapes by generating rotating excitation patterns. 

The acoustic excitation system at the TFD is combined with an optical tip-timing system for blade vibrations measurement. As the tip-timing measurement is contact-free as well, an entirely non-invasive setup has been realized.

Using the setup described above, highly flexible and realistic experimental investigations of aeroelastic phenomena in turbomachinery are possible at the TFD.

Contact

Dipl.-Ing. Christopher Meinzer

 

 

Blade Excitation with Piezo-electric Actuators

Field of Application 

  • Experimental aeroelastic excitation
  • Blade excitation in turbomachinery test rigs

Excitation System

In the project „BliDes – flutter-free compressor design“, the feasibility of controlled blade excitation with a piezo-electric actuator has been shown. To this end, multiple rotor blades of the low-speed axial compressor (LSAC) were instrumented with piezo-electric actuators for excitation and strain gauges for blade vibration measurements. The excitation signals and the measured signals are transmitted between the rotating system to the stationary system using slip rings.

With this setup, the first bending mode can be excited during compressor operation. The excitation frequency and amplitude are controlled by the power supply system. The described excitation system is fully operable and is used for aeroelastic investigations at the TFD.

Contact

Dipl.-Ing. Christopher Meinzer