Advertisement

Numerical Study on the Sound Amplification of a T-Junction with Bias Flow

  • Lin Du
  • Mikael Karlsson
  • Mats Åbom
Conference paper
Part of the Springer Proceedings in Physics book series (SPPHY, volume 185)

Abstract

This paper reports a numerical study on the aeroacoustic response of a rectangular T-junction with bias flow in the side-branch. The primary motivation of the present work is to study and explain the in recent experiments observed high sound amplification at small bias flows. The study is conducted by performing numerical simulation, which solves the 2D compressible linearized Navier-Stokes equations (LNSEs) in the frequency domain. The time averaged flow is first solved by using RANS along with a k-ε turbulence model. The overall agreement with the experimental acoustic 3-port scattering data is good. It is found that the base flow changes significantly with the presence of a small bias flow. Compared to the case with no bias flow, a strong shear layer is created along the downstream main duct by the mixed grazing-bias flow. For small bias flows (Mach-number < 0.02) this shear layers extends far downstream of the actual junction. This creates a region of vortex-sound interaction much larger than for the no bias flow case, which is the main explanation behind the large amplification.

Keywords

Shear Layer Strouhal Number Power Ratio Acoustic Power Main Duct 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

References

  1. 1.
    D. Rockwell, E. Naudascher, Review-self-sustaining oscillations of flow past cavities. J. Fluids Eng. 100, 152–165 (1978)CrossRefGoogle Scholar
  2. 2.
    J.C. Bruggeman, A.P.J. Wijnands and J. Gorter, Self-sustained low frequency resonance in low Mach number gas flow through pipelines with side branch cavities, in AIAA 10th Aero-acoustics conference, Seattle, Washington, AIAA paper 86-1924, 9–11 July 1986Google Scholar
  3. 3.
    J.C. Bruggeman, A. Hirschberg, M.E.H. van Dongen, A.P.J. Wijnands, J. Gorter, Self-sustained aero-acoustic pulsations in gas transport systems: experimental study of the influence of closed side branches. J. Sound Vib. 150, 371–393 (1991)CrossRefGoogle Scholar
  4. 4.
    S. Ziada, E.T. Bühlmann, Self-exited resonances of two side-branches in close proximity. J. Fluids Struct. 6(5), 583–601 (1992)CrossRefGoogle Scholar
  5. 5.
    S. Ziada, A flow visualization study of flow-acoustic coupling at the mouth of a resonant side-branch. J. Fluids Struct. 8(4), 391–416 (1994)CrossRefGoogle Scholar
  6. 6.
    M. Karlsson, M. Åbom, Aeroacoustics of T-junctions—an experimental investigation. J. Sound Vib. 329, 1793–1808 (2010)CrossRefGoogle Scholar
  7. 7.
    S. Föller, W. Polifke D. Tonon, Aeroacoustic characterization of T-junctions based on large eddy simulation and system identification, in AIAA aeroacoustics conference, p. 3985 (2010)Google Scholar
  8. 8.
    J. Gikadi, S. Föller, T. Sattelmayer, Impact of turbulence on the prediction of linear aeroacoustic interactions: acoustic response of a turbulent shear layer. J. Sound Vib. 333, 6548–6559 (2014)CrossRefGoogle Scholar
  9. 9.
    A. Holmberg, M. Karlsson, M. Åbom, Aeroacoustics of rectangular T-junctions subject to combined grazing and bias flows—an experimental investigation. J. Sound Vib. 340, 152–166 (2015)CrossRefGoogle Scholar
  10. 10.
    A. Holmberg, A. Kierkegaard, C. Weng, A frequency domain linearized Navier-Stokes method including acoustic damping by eddy viscosity using RANS. J. Sound Vib. (2015). doi: 10.1016/j.jsv.2015.02.030
  11. 11.
    M.S. Howe, Acoustics of Fluid-Structure Interactions (Cambridge University Press, Cambridge, 1998)CrossRefzbMATHGoogle Scholar
  12. 12.
    A. Kierkegaard, S. Boij, G. Efraimsson, A frequency domain linearized Navier-Stokes equations approach to acoustic propagation in flow ducts with sharp edges. J. Acoust. Soc. Am. 127(2), 710–719 (2010)CrossRefGoogle Scholar
  13. 13.
    S. Temkin, Elements of Acoustics (Acoustical Society of America, Melville, New York, 2001)Google Scholar
  14. 14.
    G.C.Y. Lam, R.C.K. Leung, S.K. Tang, Aeroacoustics of T-junction merging flow. J. Acoust. Soc. Am. 133(2), 697–708 (2013)CrossRefGoogle Scholar

Copyright information

© Springer International Publishing Switzerland 2016

Authors and Affiliations

  1. 1.The Marcus Wallenberg Laboratory for Sound and Vibration ResearchKTH-CCGEx, KTH-FLOWStockholmSweden

Personalised recommendations