Subproject C4 Aeroelasticity of Turbine Blades

The subproject C4 investigates the influence of regeneration-related, geometric variations of turbine blades on the aeroelastic properties of downstream blades. The focus is on the investigation of combined geometric variations. For this purpose, probabilistic approaches are used and tolerance bands are derived, which are used in the regeneration process. Another focus is on wear- and regeneration-related disturbances from upstream modules of the entire engine, which propagate as thermal streaks through the turbine. The goal is to investigate the mixing behavior and the potential to cause blade vibrations.     

MOTIVATION AND OBJECTIVES

5-stage configuration of the axial turbine test rig at the Institute of Turbomachinery and Fluid Dynamics

The blade geometry of aircraft engines deviates from the original geometry because of wear and the maintenance process. Variations are for example the thickness distribution, blade length and stagger angle. These geometry parameters can have an influence on the vibration excitation of downstream rotor cascades and have been investigated individually so far. Such deviations occur in combination in reality. To reproduce this in a model, geometries are generated based on probabilistic calculations and aeroelastic simulations are carried out. The results then allow the derivation of blade tolerance bands. With the help of these, it can be ensured that the regeneration process causes no critical vibration states. 

High-pressure turbine blades are exposed to enormous thermal loads due to the upstream combustion chamber. Therefore, the first turbine stages must be cooled. This is realized by means of air bleed from the compressor. The cooling air is directed to the blade surface via boreholes. The high thermal and aerodynamic loads cause heavy wear on film cooling holes, trailing edges and seals. Because of wear, cold streaks can propagate downstream through the turbine and cause rotor vibrations, which can shorten the lifetime of the blades. This type of excitation is investigated at the air turbine of the TFD by injecting cold streaks into the flow and measuring the resulting vibration amplitudes with a tip-timing system.

RESULTS

Using aero engine turbine guide vanes, it could be shown that regeneration-related deviations from the original geometry have a significant influence on the aerodynamic vibration excitation of the downstream blade rows. A change in the stagger angle, for example, has a significant influence on the vibration excitation of the downstream blades. The resulting oscillation amplitudes quadruple compared to the original cascade.

Example of blade wear: burn-off at blade leading edges, source of thermal streaks

CURRENT RESEARCH AND OUTLOOK

Currently, the calculated mixing behavior of cold streaks is analyzed and appropriate points of measurement are derived for later experiments. The numerical results are validated by means of the experiments. The subprojects A3 (Exhaust Gas Analysis) and A6 (Mixing and Burner Signature) are supplied with the information. In addition, a tool chain for the investigation of combined parameter variations will be set up. The results contribute to the selection of an appropriate regeneration path in the overall project.


PUBLICATIONS

International Scientific Journal Paper, peer-reviewed

  • Hauptmann, T.; Aschenbruck, J.; Seume, J. R. (2017): Forced Response Excitation due to Stagger Angle Variation in a Multi-Stage Axial TurbineInternational Journal of Gas Turbine, Propulsion and Power Systems Volume 9 (Number 3), 1--11
  • Aschenbruck, J.; Seume, J. R. (2015): Experimentally Verified Study of Regeneration-Induced Forced Response in Axial TurbinesJournal of Turbomachinery 137 (3), S. 1–10
    DOI: 10.1115/1.4028350

International Conference Paper, peer-reviewed

  • Hauptmann, T.; Meinzer, C. E.; Seume, J. R. (2018): Experimental Validation of Forced Response Methods in a Multi-Stage Axial TurbineProceedings of the ASME Turbo Expo 2018, 11-15 June 2018, Oslo, Norway, GT2018-75390
  • Hauptmann, T.; Seume, J. R. (2018): Blade Vibration Measurements in a Multi-Stage Axial Turbine with Geometric Variations2018 AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, AIAA SciTech Forum, 8-12 January 2018, Kissimmee, Florida, USA, AIAA 2018-0952
    DOI: 10.2514/6.2018-0952
  • Hauptmann, T.; Seume J.R. (2016): Aerodynamic Excitation for Variable Tip GapIn: Proceedings of ASME Turbo Expo 2016: Turbomachinery Technical Conference & Exposition
  • Schwerdt, L.; Hauptmann, T.; Kunin, A.; Wallaschek, J.; Wriggers, P.; Panning-von Scheidt, L. et al. (2016): Aerodynamical and Strucutral Analysis of Operationally used Turbine BladesIn: 5th International Conference on Through-life Engineering Services, Cranfield, England
  • Aschenbruck, J.; Hauptmann, T.; Seume, J. R. (2015): Influence of a Multi-Hole Pressure Probe on the Flow Field in Axial-TurbinesEuropean Turbomachinery Conference ETC11. Madrid
  • Hauptmann, T.; Aschenbruck, J.; Seume, J. R. (2015): Forced Response Excitation due to Variances in a Multi-Stage Axial TurbineProceedings of International Gas Turbine Congress 2015, Tokyo, Japan
  • Aschenbruck, J.; Adamczuk, R.; Seume, J. R. (2014): Recent Progress in Turbine Blade and Compressor Blisk Regeneration3rd International Conference on Through-life Engineering Services; Session: Recent Progress in Jet-Engine Regeneration, Bd. 22. Cranfield, England, S. 256–262
    DOI: 10.1016/j.procir.2014.07.016
  • Aschenbruck, J.; Seume, J. R. (2014): Experimentally Verified Study of Regeneration-Induced Forced Response in Axial TurbinesProceedings of the ASME Turbo Expo 2014, S. GT2014-25664
  • Pohle, L.; Panning-von Scheidt, L.; Wallaschek, J.; Aschenbruck, J.; Seume, J. R. (2014): Dynamic Behavior of a Mistuned Air Turbine: Comparison Between Simulations and MeasurementsProceedings of ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. Düsseldorf, Germany, S. V07BT33A015
    DOI: 10.1115/GT2014-26025
  • Aschenbruck, J.; Meinzer, C.; Pohle, L.; Panning-von Scheidt, L.; Seume, J. R. (2013): Regeneration-Induced Forced Response in Axial TurbinesASME Turbo Expo 2013Turbine Technical Conference and Exposition, June 3-7, 2013, San Antonio, Texas, USA. San Antonio, Texas, USA, S. V07BT33A010
    DOI: 10.1115/GT2013-95431
  • Aschenbruck, J.; Meinzer, C.; Seume, J. R. (2013): Influence of Regeneration-Induced Variances of Stator Vanes on the Vibration Behavior of Rotor Blades in Axial Turbines10th European Conference on Turbomachinery. Lappeenranta, Finland, S. 235–247

International Conference Paper, not peer-reviewed

  • Ernst, B.; Seume, J. R.; Herbst, F. (2016): Probabilistic CFD-Analysis of Regeneration-Induced Geometry Variances in a Low-Pressure TurbineIn: 52nd AIAA/SAE/ASEE Joint Propulsion Conference, Propulsion and Energy Forum, Salt Lake City, Utah, USA, S. AIAA 2016--4555.
  • Hauptmann, T.; Aschenbruck, J.; Christ, P.; Hennecke, C.; Dinkelacker, F.; Seume, J. R. (2015): Influence of Combustion Chamber Defects on the Forced Response Behavior of Turbine Blades. Proceedings of the 14th International Symposium on Unsteady Aerodynamics, Aeroacoustics & Aeroelasticity of Turbomachines, ISUAAAT14, 8-11 September 2015, Stockholm, Schweden, S. 9

National Scientific Journal Paper, not peer-reviewed

  • Hohenstein, S.; Aschenbruck, J.; Seume, J. R. (2013): Einfluss betriebs- und regenerationsbedingter Varianzen von TurbinenschaufelnInternational Journal for Electricity and Heat Generation VGB PowerTech 2013 (11), S. 51–58

National Conference Paper, not peer-reviewed

  • Aschenbruck, J.; Meinzer, C.; Seume, J. R. (2014): Regenerationsbedingte Nachlauferregung in AxialturbinenInstationäre Aerodynamik und Aeroelastik in Turbomaschinen. Institut für Energietechnik, Ruhr-Universität Bochum. Bochum, 05.03.2014
  • Aschenbruck, J.; Weidlich, N.; Herde, F.; Seume, J. R. (2011): Nachhaltige Regeneration von FlugzeugtriebwerkenDLRK 2011 in der Session Innovation aus Niedersachsen Leichtbau und Triebwerktechnik. German Society for Aeronautics and Astronautics. Bremen, 01.01.2011
All publications of the Collaborative Research Centre

SUBPROJECT LEADER

Prof. Dr.-Ing. Jörg Seume
Address
An der Universität 1
30823 Garbsen, Raum 315
Address
An der Universität 1
30823 Garbsen, Raum 315

STAFF