Frank Kameier Professor for Fluid Mechanics and Acoustics - PowerPoint PPT Presentation

slide1 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Frank Kameier Professor for Fluid Mechanics and Acoustics PowerPoint Presentation
Download Presentation
Frank Kameier Professor for Fluid Mechanics and Acoustics

play fullscreen
1 / 53
Frank Kameier Professor for Fluid Mechanics and Acoustics
239 Views
Download Presentation
caine
Download Presentation

Frank Kameier Professor for Fluid Mechanics and Acoustics

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Frank Kameier Professor for Fluid Mechanics and Acoustics Unsteady Aerodynamics in Turbomachines • Rotating Stall and Surge • Rotating Instabilities and Blade Vibrations (Flow-induced Vibrations) • The „Demonstrator“ of FH Düsseldorf

  2. Rotating Instabilities Rotating Stall Surge Operating Map (Compressor)– non dimensional Design Conditions

  3. y j Flow Separation in a Turbomachine(Compressor) NGV Dresden „Abrupt Stall“

  4. y j Surge Conditions High Pressure CompressorA pressure wave with an amplitude of several bar propagates from rear to front stages. Damage of the rotor blades after app. 1000 surge cycles.

  5. Instrumentation – Wall Pressure Transducers - Kulite XT190  4 mm Piezo-resisitive (DC up to 30 kHz)

  6. Temperature Wall pressure Surge Test Nhrt=60% Expansion

  7. Wall Pressure Fluctuations at Surge Conditions

  8. Wall Pressure Fluctuations at Bang-Test-Conditions axial shot = plane wave

  9. Wall Pressure Fluctuations at Bang-Test-Conditions lateral shot = non plane wave

  10. Surge Analysis in a 10-Stage Compressor

  11. Rotating Instabilities – a Periodic Vortex Shedding? Flow around a cylinder R.Feynman, Lectures on Physics, 1974

  12. Kármán Vortex Separation Causes Mechanical Damage Ferrybridge, England 1965 Ref.: Sahlmen, Niemann http://www.aib.ruhr-uni-bochum.de/

  13. Kármán Vortex Separation Causes “Stall Flutter”

  14. Rotating Instabilities – a Wall Shear Stress Fluctuation? Schlichting, Boundary Layer Theory

  15. Rotating Instabilities and Blade Vibrations Restricted speed range Blade vibrations - rotating frame of reference - Wall pressure fluctuations - fixed frame of reference - BAUMGARTNER, KAMEIER, HOURMOUZIADIS, ISABE Conference, Melbourne, 1995

  16. Rotating Instabilities and Blade Vibrations Wall pressure fluctuations - fixed frame of reference - Blade vibrations - rotating frame of reference -

  17. Tip Clearance Effect of an Axial Flow Machine

  18. High pressure compressor 13200 U/min Low speed fan 1400 U/min

  19. High Pressure Compressor – Speed Variation p[Pa] f[Hz] t[s]

  20. Acoustic Resonances – Aero Engine Occurence Speed of sound is the speed of propagation • Helmholtz-Resonator • Standing waves and orifice resonance bzw. Sharp peak! • Self-induced acoustical resonances - „Parker Modes“ – Orgen-pipe resonances [Hz]

  21. “Acoustic Resonance” Downstream of a Flat Plate in Flow Quelle: Parker, Aeroacoustics, International Journal of Fluid Dynamics, 1997 http://www-vhost.monash.edu.au/elecpress/ijfd/1997_vol1/paper1/Parker.Flow.html

  22. Wall Pressure Fluctuations Upstream Rotor 1(HPC) Operating conditions on secondary characteristics y j Rotating stall

  23. Wall Pressure Fluctuations Upstream Rotor 1(HPC) Operating conditions close to design y j Transonic flow in the blade tip region

  24. Rotor 1 Redesign - Wall Pressure Fluctuations Operating conditions close to surge margin y Redesign j

  25. Circumferential Distribution of Rotating Instabilities Wall Pressure Fluctuations Power spectrum Coherence Phase spectrum

  26. Rotating Stall as a Special Case of Rotating Instabilities „Rotating Stall“

  27. Rotating Stall in a Compressor Blade Row

  28. Negative Frequencies and Rotating Stall

  29. Rotating Stall – Part Span Stall Fixed frame Rotor frame Turbotech II - Teilvorhaben Nr. 1.244

  30. Historical Review: „Instabilities“ in the Atmosphere of the Earth A circumferential propagating Kármán vortex street: Rossby-wave (Chen, Haupt, Rautenberg, Uni Hannover, 1987)

  31. Rotating Stall in a Centrifugal Impeller Quelle: Bohl, Strömungsmaschinen, 1994

  32. Sound Generation by Rotating Stall in Centrifugal Turbomachines Rotating Instability Inlet Duct Impeller Blade (Mongeau, Pennsylvania State University, 1991)

  33. Rotating Instability Waves in a Ducted Axial Fan (Krane, Bent, Quinlan, AT&T Bell Laboratories, 1995)

  34. Rotating Instabilities in a Steam Turbine (Low Pressure Stage) Power spectrum Coherence along circumference vgl.: Truckenmüller, Gerschütz, Stetter, Hosenfeld, Uni Stuttgart, ImechE, London 99

  35. Rotating Instabilities - Periodical Unsteady Flow Field Within aRotor Blade Row of an Axial Compressor (TU Dresden) vgl.: Mailach, Vogler, Lehmann, TU Dresden, ASME Montreal 2007

  36. Rotating Instabilities Rotating Stall  separated flow  randomised behaviour  turbulent  frequencies are not related to the number of rotor blades separated flow  discrete behaviour periodical frequencies are related to the number of rotor blades

  37. Correlation of Vibration and Pressure Fluctuations – Measurements on the Demonstrator of FH Düsseldorf (Co-op Rolls-Royce Germany)

  38. Unsteady Instrumentation – Fixed Frame of Reference Transducers - 16 ¼‘‘ MicrofonesMicrotech MK301. • Accelerometer B&K 4371 • Polytec Laservibrometer Transducer positions - 84 circumferential positions,  = 4.285°. - 6 positions in the rotor wake region,  = 60°.

  39. Blades with transducers Unsteady Instrumentation – Rotating Frame of Reference Transducer - 4 Pressure transducersKulite LQ-47 und LQ125 - Strain Gages HBM - Rotating 8-chanel amplifier unitDLR Berlin,4 x Kulites, 4x Strain Gage - 10 – chanel slip ring unit

  40. Pressure Transducers LQ-47, LQ125 Strain Gage Unsteady Instrumentation – Rotating Frame of Reference Transducer - 4 Pressure transducersKulite LQ-47 und LQ125 - Strain Gages HBM - Rotating 8-chanel amplifier unitDLR Berlin,4 x Kulites, 4x Strain Gage - 10 – chanel slip ring unit

  41. 10-Channel Slip-ring 8-Channel amplifier unit (rotating) Unsteady Instrumentation – Rotating Frame of Reference Transducer - 4 Pressure transducersKulite LQ-47 und LQ125 - Strain Gages HBM - Rotating 8-chanel amplifier unitDLR Berlin,4 x Kulites, 4x Strain Gage - 10 – chanel slip ring unit

  42. Rotating Frame of Reference,  = 60°, 1000min-1, f = 1Hz Fixed Frame of Reference,  = 60°, 1000min-1, f = 1Hz j j 0.18 0.16 0.09 0.17 0.15 0.14 0.13 0.12 0.11 0.10 0.06 0.05 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.10 0.09 0.05 0.06 Continuous Throttle Procedure n=1000min-1 – Wall Pressure Excitation of Modes  = 20 ... 9

  43. j j 0.17 0.17 0.16 0.16 0.15 0.15 0.14 0.14 0.13 0.13 0.12 0.12 0.11 0.11 0.10 0.10 0.09 0.09 0.06 0.06 0.05 0.05 Continuous Throttle Procedure n=1000min-1- Rotating Frame of Reference (Strain Gauge) - Soft Blade feigen ~ 69Hz Stiff Blade feigen ~ 97Hz Excitation of Modes  = 20 ... 9

  44. j 0.20 0.19 0.17 0.16 0.15 0.10 0.05 Continuous Throttle Procedure n=1000min-1- Increased Blade Loading - Fixed Frame of Reference – Rotating Stall Excitation of Modes  = 5, 6, 6.5 und 7

  45. Histogram of Rotating Stall amplitudes Histogram of Rotating Instability amplitudes Gauß Distribution Rotating Stall Rayleigh Distribution RI-Frequenzen Umgebungsrauschen Statistical Analysis of Rotating Instability and Rotating Stall

  46. Rotating Stall and Rotating Instabilities Rotating Instabilities(Schematical Sketch) Rotating Stall(Schematical Sketch) Stall region „primary“ - Characteristics

  47. Small Gap Large Gap Tip Clearance Flow Starting Hypothesis Point of separation No secondary flow region, no separated boundary layer Small Gap Large Gap Secondary flow region Small Gap Large Gap Flow visualization - Single stage compressor along throttling procedure Flow Field with RI j Rotorblade Quelle: Kameier 1994.

  48. Low Flow Rate High Flow Rate Separated Flow Region Separated Flow Region

  49. Low Flow Rate High Flow Rate Separated Flow Region Separated Flow Region

  50. Tip Clearance Variation Tip Clearance s*= 0%, Low Flow Rate Tip Clearance s*= 2%, Low Flow Rate