1. 1 TURBO POWER Program Conference April 13-14, 2011, Göteborg Overview of Aeromechanical Research at KTH Energy Technology Damian Vogt, KTH 2011-04-13

2. 2 Concerned with interactions between fluid and structure, both from a static and a dynamic point-of-view Aeromechanics These interactions can be harmful to machine integrity  overload, HCF

3. 3 Aeromechanics in Turbomachines Excitation of structural components by flow External sources: forced response Self-excited: flutter  Unless properly damped, these vibrations might lead to material fatigue

4. 4 Which are the turbomachines that are typically affected?

5. 5 Industrial gas turbines Aircraft engines Wind turbines

6. 6 How green is aeromechanics?

7. 7 Aeromechanics and Sustainability Aeromechanics by itself is not driving up the efficiency of your machine, but …  Aeromechanics is one of the primary (if not THE) key enabling technology to ensure sustainable, reliable and affordable energy supply of the future … a machine that is not aeromechanically safe will disintegrate In the perspective of developing the next generation of more sustainable turbomachines New processes drive machines into new (and aeromechanically unexplored) operating regimes The design of the next generation of turbomachines is increasingly relying on numerical predictions Current trends are in direction of reduced component count, longer time between overhauls, at unchanged power output

8. 8 Effects on TURBO POWER Goals Better control of vibration allows earlier and a more rapid introduction of new technologies  New designs  Retrofits Improvements of availability of machines HCF toolbox improvements  Valid both for turbines and compressors Increased confidence in using numerical prediction tools

9. 9 Flutter-Free Turbomachinery Blades www.future-project.eu www.future-project.eu Presentation of FUTURE Project

10. 10 FUTURE Project Partners Industry Research Institutes Academia Duration 2008-2012, budget: 10.6M€ Lead

11. 11 Expected Benefits The FUTURE project shall contribute to making turbomachinery aeroelastic predictions more reliable Numerical tools validated on new, relevant and unique aeroelastic test cases that shall lead to best practice guidelines Achieving this will … … help making turbomachinery blades flutter-free … make new aircraft engines more efficient … cut development costs and time frames  The FUTURE project will provide key enabling technologies towards a green, safe, reliable and affordable air transport of the future

12. 12 Offshore Wind Enabling Technology www.innoenergy-initiative.com www.innoenergy-initiative.com Presentation of OFFWINDTECH Project

13. 13 OFFWINDTECH Project Partners Industry Research Institutes Academia Duration 2011-2013, budget: 8M€ Lead

14. 14 Expected Benefits The OFFWINDTECH project shall contribute to making the next generation of off-shore wind parks feasible Very large wind turbines Deep water  From an aeromechanical point of view this is extremely interesting and it pushes our design and analysis methods into new areas Achieving this will … … open up for increasing the share of wind power in the global energy mix … make an advanced analysis tool accessible to the wind turbine industry  dual use  The OFFWINDTECH project will provide key enabling technologies towards the next generation of off-shore wind turbines, both aero/aeromech and system-wise

15. 15 How do we ensure that new findings are disseminated to today’s and tomorrow’s engineers?

16. 16 TurbomacHinery AeRomechanical UniverSity Training www.explorethrust.eu www.explorethrust.eu Presentation of THRUST Programme

17. 17 THRUST Partners AcademiaIndustry/Research Institutes  The world’s first Master’s Programme in Turbomachinery Aeromechanics

18. 18 Programme Overview

19. 19 e n a b l i n g s u s t a i n a b i l i t y

20. 20 TURBO POWER Program Conference April 13-14, 2011, Göteborg WP1, WP2 & Synthesis Compressor Technology María Mayorca, KTH Nenad Glodic, KTH Florian Fruth, KTH Damian Vogt, KTH 2011-04-13

21. 21 AROMA – Aeroelastic Reduced Order Modeling Analyses Back Expansion WP1 WP2 Synthesis

22. 22 Beyond State-of-the-Art What is new Integration of the Aeromechanical Design Change in a Numerical Tool New methods for the prediction of aero-coupled mistuned analyses Estimation of the contribution of different parts of the aeromechanical design chain to the final fatigue risk Challenges Standardization of aeromechanical practices Adaptability to different FE and CFD solvers Keep up with new emerging methods and techniques Consideration of mistuning

23. 23 Hulda, Validation Case Tip Timing Data from VAC Resonance Crossing Mode 4, 3300Hz Rpm: 13201 15EO ND8 Forward Nominal Case VIGV 0 deg Amplitude: 0.136 +/- 0.005mm 5 Frame 15 VIGV 23 Rotors 51 Stators 8 OGV

24. 24 How can we predict the response?

25. 25 Numerical Structural Domain Blisk Structural Model (Finite Element) Pre-stressed Conditions (OP) Crossing OK at 3302.5Hz OP

26. 26 Nominal Case, 0deg VIGV Steady State at OP (CFD) Test DP Validation OP

27. 27 Unsteady CFD Analysis, Forced Response Scaled Sector 1 strut  5EO 3 VIGV  15EO 5 R1  25EO 10 S1  50EO

28. 28 Harmonic Forces Rotor Cylindrical Integrated Force 15EO indicated Fgen=0.106N (generalized force M4)

29. 29 Aerodynamic Damping Extract Mesh Rotor Domain Extract Initial Solution from SS Stage Extract inlet and outlet profile BC Extract M4 and frequency to import to Linearized Navier Stokes solver Solve TWM, include ND8 Mode 4 Very localized 8ND, 0.42%

30. 30 Reduced Order Modeling (ROM) Blade nodes: 11+1 (same as in MLS) Disk nodes: 7 (at the outer part) M4 8ND

31. 31 Forced Response 8ND (Tuned) Freq: 3289Hz M4 Blisk ROM Max amp: 0.042mm Dr=0.42% Test: 0.136+/- 0.005mm 3 times lower

32. 32 Where do the differences come from?

33. 33 Structural Perturbations (Mistuning) Maximum Amplitude Magnification: 1.55

34. 34 Forcing Predictions (WP1) Effect of Scaling of Blade Row Sectors “… a rule of thumb is suggested to not exceed 5% total scaling ratio…”

35. 35 Mesh sensitivity in prediction of aerodynamic damping Difference in predicted aerodynamic damping up to ~50 % !

36. 36 Aerodynamic Perturbations Considerations (WP2) Monte Carlo 1000 cases Each 5th blade randomly mistuned In ~85% of cases stability has increased (for this particular case) Observed deviation of aerodynamic damping value due to asymmetries was ~15% from the tuned case unstable TWM stability curve stable Cumulative probability

37. 37 How can we design for a reduced fatigue risk?

38. 38 Physical Understanding of Unsteady Aerodynamics Effect of the Blade Count Ratio on the Aerodynamic Forcing (WP1) Lower FORCING

39. 39 Development of Integrated Methods

40. 40 Including Mistuning ROM, MLS Tuned Mistuned Aerodynamic Damping Forced Resposne Amplitude Magnification Interacting Modes

41. 41 Overall Target

42. 42 Research Efforts Planned Validation with Tip Timing Test Data HULDA compressor, M4, 15EO Estimation of “accuracy” and “physical effects” throughout the chain from the preliminary state currently shown As the research in the other WP:s continue their results will be picked up in the synthesis

43. 43 Dissemination Activities WP1 Name (Main author)TitleType Maria MayorcaEffect of Scaling of Blade Row Sectors on the Prediction of Aerodynamic Forcing in a Highly- Loaded Transonic Compressor Stage ASME J. of Turbomachinery (2010) Florian FruthInfluence of the Blade Count Ratio on Aerodynamic Forcing – Part II: Turbine ASME Paper (2011) Maria MayorcaEffect of Scaling of Blade Row Sectors on the Prediction of Aerodynamic Forcing in a Highly- Loaded Transonic Compressor Stage ASME Paper (2009) Florian FruthInfluence of the Blade Count Ratio on Aerodynamic Forcing – Part I: Compressor ASME Paper (2010) Seyed Mohammad Hosseini Effect of Scaling of Blade Row Sectors on the Prediction of Aerodynamic Forcing in a High- Pressure Transonic Turbine Stage ASME Paper (2011) Jesus de AndradeEffect of the scaling technique of blade row sectors on the prediction of aerodynamic forcing MSc thesis (2008) Seyed Mohammad Hosseini Aeromechanic Analysis of an Industrial HPT Rotor MSc thesis (2010) Adrián García DomingoValidation of a Harmonic Balance Method for Prediction of Aerodynamic Forcing MSc thesis (2010) Antonio SanzParametric Study … Part IIA: Forced Response Behavior of a Turbine MSc thesis (2010) Alessio ContranParametric Study of … Part IIB: Forced Response Behavior of a Compressor MSc thesis (2010) Journal Journal Recommend. Paper Thesis

44. 44 Dissemination Activities, WP2 Name (Main author)TitleType Nenad GlodicExperimental and Numerical Investigation of Aeroelastic Properties of Combined Mode Shapes in an Oscillating LPT Cascade ISUAAAT Paper (2009) Damian VogtThe Effect of Unsteady Aerodynamic Asymmetric Perturbations on the Mode Shape Sensitivity of an Oscillating LPT Cascade ISUAAAT Paper (2009) Nenad GlodicExperimental and Numerical Investigation of Mistuned Aerodynamic Influence Coefficients in an Oscillating LPT Cascade ASME Turbo Expo (2011) Michael BarteltNumerical and Experimental Investigation of Aeroelastic Properties of Combined Modes in an Oscillating LPT Cascade MSc thesis (2008) Yaoguang ZhaiFlutter Analysis of Transonic Compressor RotorsMSc thesis (2009) Carlos GomezInvestigation of … - Part I: Direct Simulations of Influence Coefficients MSc thesis (2009) Muhammad ShabanInvestigation of … - Part II: Travelling Wave Mode Approach MSc thesis (2010) Guillaume GondreParametric Study … - Part III B: Aerodynamic Damping Behavior - Turbine Profiles MSc thesis (2010) Lucio MonacoParametric Study … - Part III A: Aerodynamic Damping Behavior - Compressor Profiles MSc thesis (2010) Pedro HernándezMesh Sensitivity Study…- Part I: Turbine cascadeMSc thesis (2011) Miguel RodriguezMesh Sensitivity Study…- Part II: Compressor cascade MSc thesis (2011) Journal Paper Thesis

45. 45 Dissemination Activities, Synthesis Name (Main author)TitleType Maria MayorcaA new reduced order modeling for stability and forced response analysis of aero-coupled blades considering various mode families ASME Paper (2010) Hans MårtenssonSimplified Forced Response HCF Assessment of Turbomachinery Blades ASME Paper 2009 Maria MayorcaNumerical Tool for Prediction of Aeromechanical Phenomena in Gas Turbines ISABE Paper (2009) Maria MayorcaPrediction of Turbomachinery Aeroelastic Behavior from a Set of Representative Modes ASME Paper (2011) Damian VogtEffect of Reduced Order Modeling on the HCF Assessment of a Transonic Compressor IFToMM Paper (2009) Pierre-Emmanuel Laurens Effect of ROM Size on Prediction Accuracy of HCF Behavior of a Transonic Compressor Stage Thesis (2009) Maria MayorcaDevelopment and Validation of a Numerical Tool for Aeromechanical Analyses in Turbomachinery Tek Lic Thesis (2010) Journal Paper MSc Thesis Lic Thesis

46. 46 e n a b l i n g s u s t a i n a b i l i t y