Summary

In this project a contribution to the physical understanding of low-frequency excitation with amplitudes on the unsteady blade response will be made. The causes for such excitations are often not predictable or can only be inadequately modeled, but can lead to fatigue damage of compressor blades.

The experiments are conducted at the test facility for aeroelastic investigations of the chair for aero engines of TU Berlin. The measurement section of the facility consists of a large-scale compressor cascade with eleven blades. With stepper motors, nine of the blades can be forced to vibrate in torsion and plunging mode. The modular character of the facility permits the integration of a mechanism for generating a periodic unsteady inlet low, which can be installed upstream of the compressor cascade. In this way different excitation patterns can be realized within the framework of the research project. The unsteady aerodynamic blade response in the absence and presence of a periodically unsteady inlet flow can be measured. Therefore, the proposed basic experiment is capable of investigating how low-frequency excitations with small amplitudes influence the blade response. Through the variation of the parameters and a detailed investigation of the phase between excitation and blade motion, it is also assessed whether the response problem can be described with linear theory.

The investigations will be performed by means of state of the art technology. Hot wire measurement technology will be used to characterize the periodic unsteady inflow. The unsteady aerodynamic pressure distribution along the blade surface is measured with piezoresistive pressure transducers and the vibration frequency and amplitude with strain gauges.

Person of contact: M.Sc. Leonie Malzacher

Experimental Investigation of an Aerodynamically Mistuned Oscillating
Compressor Cascade
L. Malzacher, C. Schwarze, V. Motta, D. Peitsch
Journal of Turbomachinery, Volume 141, Issue 7, 071012 (9 pages), July 2019
DOI: 10.1115/1.4043474 [2]

A Low-Speed Compressor Test Rigfor Flutter Investigations
L. Malzacher, S. Geist, D. Peitsch, H. Hennings
Joumal of Turbomachinery, Volume 141, Issue 5, 051009 (12 pages), May 2019
DOI: 10.1115/1.4041817 [3]

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