Subproject C6 Aeroelasticity of Multi-Stage Axial Compressors

The aeroelasticity of mistuned axial compressors with multiple stages is investigated. By using an improved simulation methodology, the influence of regeneration on the vibration behavior of compressor blisks is analyzed. The focus is on the structural and aerodynamic coupling of compressor blades between different stages.

MOTIVATION AND OBJECTIVES

Axial compressor rig at the Institute of Turbomachinery and Fluid Dynamics

In modern aircraft engines blade integrated disks (Blisks) are used more and more, because they permit a high pressure ratio per stage while being lightweight. Due to their low mechanical damping, they are highly sensitive to vibration excitation. Geometrical variances caused by wear and regeneration have a significant influence on the vibrational behavior.  The main goal is therefore the prediction of the operational vibrational behavior of multistage compressors, while considering these variances. The results enable accurate part life predictions.

RESULTS

The current project results from the fusion of the sub-projects C6 “Aeroelasticity of Compressor Blisks” and C3 “Regeneration-induced Mistuning”. In the sub-project C6, the influence of (regeneration-induced) geometric variances on the vibrational behavior of an axial compressor blisk was analyzed, focusing on blend repairs. This influence was quantified in simulations, and shown in measurements using a blisk geometry designed for this purpose. The calculated aerodynamic damping was used in the sub-project C3 to enable more accurate simulations of the vibrational behavior. In this case, mistuning was focused – deviations from the cyclic symmetry. A model order reduction method developed earlier was extended to enable the consideration of deviations in the disk segments.

CURRENT RESEARCH AND OUTLOOK

Currently there are two main goals: Extending the models to include multiple stages, and  a direct integration of geometric variances into the reduced order model. In multi-stage models, the vibration excitation and response contain multiple harmonics which has to be considered. The stator angle of attack (of the stator vanes) is varied  in order to realize this kind of excitation in the axial compressor (at TFD). In the end an integrated simulation method is developed that, together with the sub-projects B4 and C5, enables fast and accurate part life prediction for axial compressors. This represents an important contribution to the decision on the regeneration path.


PUBLICATIONS

All publications of the Collaborative Research Centre

SUBPROJECT LEADER

Prof. Dr.-Ing. Jörg Seume
Address
Appelstraße 9
30167 Hannover
Address
Appelstraße 9
30167 Hannover
Dr.-Ing. Lars Panning-von Scheidt
M. Sc. Mona Amer
Address
Appelstraße 9
30167 Hannover
Building
Room
008
Address
Appelstraße 9
30167 Hannover
Building
Room
008