Modelling of Trailing Edge Flow Tones in Elastic Structures

  • W. K. Blake
  • J. L. Gershfeld
  • L. J. Maga
Conference paper
Part of the IUTAM Symposia book series (IUTAM)

Abstract

The hydroelastic coupling of turbine blade vibration modes and trailing edge vortex shedding from the blade is a well known phenomenon that leads to intense audible tones and shortened fatigue life. Historically, most researches on such turbo-blade “singing” have focussed on the prediction of the vortex shedding frequency and on the reduction of offending vibration levels by reshaping the trailing edges. The associated control measures effectively permit the “detuning” of the vortex shedding from the blade modes, and the effectiveness of such measures is more or less qualitatively known. This paper builds on and extends a different line of research that is aimed at merging the controling fluid dynamic and structural dynamic factors of these flow-induced tones into a quantitative semiempirical model of the non linear flow-induced vibration of turbo machine blading. The elements of the model development involve the use of measured nonlinear “wake impedances” by the forced motion of trailing edges, the development of a mathematical model for the response of blade structures that are coupled to the wake dynamics, and finally the testing of the modeling against measured flow-induced vibration of simple hydrofoils. The parameters used in both the modeling and the experimental verification include structure mass density, hydrofoil geometry, damping, and trailing edge geometry.

Keywords

Fatigue Vortex Epoxy Vorticity Styrofoam 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Bearraan, P.W. (1965) “Investigation of the Flow Behind a Two-Dimensional Model With a Blunt Trailing Edge and Fitted with Splitter Plates” J. Fluid Mech. 21, 241–255, 1965.ADSCrossRefGoogle Scholar
  2. 2.
    Blake, W.K. (1984a) “Excitation of Plates and Hydrofoils by Trailing Edge Flows” Trans. A.S.M.E. Journal of Vibration, Acoustics, Stress, and Reliability in Design 106, 351–363, 1984.CrossRefGoogle Scholar
  3. 3.
    Blake, W.K. (1984b) “Trailing Edge Flow and Aerodynamic Sound, Part I. Tonal Pressure and Velocity Fluctuations, Part II. Random Pressure and Velocity Fluctuations” DTNSRDC Report 83/113 Dec. 1984.Google Scholar
  4. 4.
    Blake, W.K. (1984c) “Aero-Hydroacoustics For Ships” Vol. I and Vol. II DTNSRDC Report 84/010 June 1984.Google Scholar
  5. 5.
    Blake, W.K., Gershfeld, J. and Maga, L.J. (1986) “Self-Excited Vortex Driven Vibration of Hydrofoils of Varying Densities and Geometries” DTNSRDC Report in PreparationGoogle Scholar
  6. 6.
    Blake, W.K. and Maga, L.J. (1975) “On the Flow-excited Vibrations of Cantilever Struts in Water. 1. Flow-induced Vibration and Damping” J. Acous. Soc. Am. 57, 610–625, 1975.ADSCrossRefGoogle Scholar
  7. 7.
    Blake, W.K. and Maga, L.J. (1979) “Near-Wake Stucture and Unsteady Pressures at Trailing Edges of Airfoils” IUTAM/ICA/AIAA Proc. Symp. Mechanics of Sound Generation in Flows, Gottungen, Pg. 1979 Springer-Verlag, Pub.Google Scholar
  8. 8.
    Blake, W.K., Maga, L.J., and Finkelstein G. (1977) “Hydroelastic Variables Influencing Propeller and Hydrofoil Singing” ASME Symposium on Flow Induced Noise and Vibration. Atlanta, Ga.Google Scholar
  9. 9.
    Graham, J.M.R. (1967) “The Effect of End Plates on the Two-Dimensionality of a Vortex Wake” Aero. Quarterly. 20, 237–247, 1969.Google Scholar
  10. 10.
    Heskestad, G. and Olberts, D.R. (1960) “Influence of Trailing Edge Geometry on Hydraulic-Turbine Blade Vibration” Trans. A.S.M.E., J. Eng. for Power 82, 103–110, 1960.CrossRefGoogle Scholar
  11. 11.
    Hartlen, R.T. and Currie, I.G. (1970) “Lift-Oscillator Model of Vortex-Induced Vibration” Proc. J. Eng. Mech. Div., Am. Soc. Civ. Eng. 96, 577–591,Google Scholar
  12. 12.
    Nayfeh, A.H. and Mook, D.T. (1979) “Non-linear Oscillations” J. Wiley and Sons.Google Scholar

Copyright information

© Springer, Berlin Heidelberg 1986

Authors and Affiliations

  • W. K. Blake
    • 1
  • J. L. Gershfeld
    • 1
  • L. J. Maga
    • 1
  1. 1.David Taylor Naval Ship R&D CenterBethesdaUSA

Personalised recommendations