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Aircraft noise generation and assessment

Aeroacoustic wind tunnel design
  • J. Pereira GomesEmail author
  • A. Bergmann
  • H. Holthusen
Original Paper
  • 1 Downloads

Abstract

Further progress in airframe noise research including noise prediction and noise reduction solutions depends on the availability of aeroacoustic wind tunnel test facilities with superior aerodynamic and acoustic quality. The demand for aeroacoustic wind tunnels with extremely low background noise and pressure fluctuations, yet with a relevant test section cross-section area and flow velocity, increased significantly over the last decade. In the future, this demand will continue to grow to cope with the challenging noise reduction objectives for aviation noise defined for the years to come. The present text is focused on the state-of-the-art aeroacoustic wind tunnels available today and their design. The design guidelines discussed here assume a classic aerodynamic wind tunnel as a baseline. Therefore, the present text is addressed to both those who are interested in the design of a completely new aeroacoustic wind tunnel as well as those interested in the acoustic upgrade of an existing aerodynamic wind tunnel. As a direct consequence of the multi-disciplinary nature of this complex task, and the multitude of solutions and design tools that are required to complete it, the approach followed here subdivides the design of the aeroacoustic wind tunnel into four main sections: wind tunnel airline circuit (includes the first and second airline cross legs), drive unit and anechoic plenum. While the design approach for the airline circuit and the drive unit is strongly based on coupled numerical solutions of CFD and acoustic solvers, the design of the acoustic plenum gives more emphasis to in situ observations and to experimental results. The main sections of the aeroacoustic wind tunnel and their best design are discussed separately in this contribution.

Keywords

Aeroacoustic Aerodynamic Wind tunnel Acoustics 

List of symbols

A

Area, m\(^2\)

\(A_0\)

Reference area (\(= 1~\hbox {m}^2\)), m\(^2\)

\(A_{\text {p}}\)

Wall partition area, m\(^2\)

c

Speed of sound, m/s

\({C_{{\text {p}},_{{\text {RMS}}}}}\)

Pulsating coefficient

d

Duct diameter, m

f

Frequency, Hz

h

Brightness per histogram level

\(\kappa\)

Ratio of specific heats

L

Length, m

l

Duct length, m

\(l_{{\text {ef}}}\)

Effective duct length, m

\(L_{\text {m}}\)

Overall brightness level

\(L_p\)

Sound pressure level

\({L_{{\text {p}},_{{\text {OSPL}}}}}\)

Overall sound pressure level

\(\varDelta f\)

Frequency bandwidth, Hz

\(\varDelta L_{\text {p}}\)

Acoustic damping

\(\varDelta p_{{\text {loss}}}\)

Pressure loss

\(\lambda\)

Wavelength, m

\(\dot{m}\)

Mass flow rate, kg/s

Ma

Mach number

p

Pressure, N/m\(^2\)

\(p_0\)

Reference pressure (\(= 20~\mu\)Pa), N/m\(^2\)

\(p_{{\text {tot}}}\)

Total pressure, N/m\(^2\)

r

Distance, m

\(r_0\)

Offset of the acoustic centre along the measurement path, m

\(R'_{\text {I}}\)

Apparent intensity sound reduction index

\(\rho\)

Flow density, kg/m\(^3\)

U

Flow velocity, m/s

V

Volume, m\(^3\)

Abbreviations

ARC

Active resonance control

atm

Atmospheric

BBN

Broadband noise

BPF

Blade passing frequency

CFD

Computational fluid dynamics

DLR

German Aerospace Centre

DNW

German–Dutch Wind Tunnels foundation of DLR and NLR

in

Inlet

inc

Incident

LLF

Large low-speed facility

NLR

Netherlands Aerospace Centre

NWB

Low speed wind tunnel Braunschweig

OSPL

Overall sound pressure level

out

Outlet

SPL

Sound pressure level

trs

Transmitted

References

  1. 1.
    Becker, K., Heitkamp, K., Kgeler, E.: Recent progress in a hybrid-grid CFD solver for turbomachinery flows. In: Proceedings of the \(5^{th}\) European Conference on Computational Fluid Dynamics ECCOMAS CFD \(2010\), Lisbon (2010)Google Scholar
  2. 2.
    Bertram, M., Deines, E., Mohring, J., Jegorovs, J., Hagen, H.: Phonon tracing for auralization and visualization of sound. In: Proceedings of IEEE Visualization (2005)Google Scholar
  3. 3.
    Broszat, D., Selic, T., Marn, A.: Verification of the inverse cut-off effect in a turbomachinery stage—Part 1—numerical results. In: \(18^{th}\) AIAA/CEAS Aeroacoustics Conference, Colorado Springs, Colorado (2012)Google Scholar
  4. 4.
    Broszat, D.U., Selic, T., Marn, A.: Verification of the inverse cut-off effect in a turbomachinery stage—Part 2—comparison to experimental results. In: \(19^{th}\) AIAA/CEAS Aeroacoustics Conference, Berlin (2013)Google Scholar
  5. 5.
    Brown, K., Devenport, W., Borgoltz, A.: Exploiting the characteristics of Kevlar-Wall wind tunnels for conventional aerodynamic measurements. In: AIAA AVIATION \(2014\)\(30^{th}\) AIAA Aerodynamic Measurement Technology and Ground Testing Conference, Atlanta, Georgia (2014)Google Scholar
  6. 6.
    Camargo, H., Remillieux, M., Burdisso, R., Crede, E., Devenport, W.: The Virginia Tech stability wind tunnel from an aerodynamic into an aeroacoustic facility. In: \(19^{th}\) International congress on acoustics, Madrid (2007)Google Scholar
  7. 7.
    Cremer, L., Mueller, H.A.: Principles and Applications of Room Acoustics, vol. 1. Peninsula Publishing, Newport Beach (2016) (ISBN 0932146732) Google Scholar
  8. 8.
    Eisinger, F.L., Sullivan, R.E.: Unusual acoustic vibration in heat exchanger and steam generator tube banks possibly caused by fluid-acoustic instability. J Eng Gas Turbines Power 115(2), 411–417 (1993)CrossRefGoogle Scholar
  9. 9.
    Envia, E., Nallasamy, M.: Design selection and analysis of swept and leaned stator concept. J. Sound Vib. 228(4), 793–836 (1999)CrossRefGoogle Scholar
  10. 10.
    Gurin, S., Moreau, A., Tapken, U.: Relation between source models and acoustics duct modes. In: \(16^{th}\) AIAA/CEAS Aeroacoustics Conference, Miami, Florida (2009)Google Scholar
  11. 11.
    Gurin, S., Moreau, A.: Accounting for sweep and lean in the design-to-noise of rotor-stator stages. In: Proceedings of the DAGA Conference, Berlin (2010)Google Scholar
  12. 12.
    Holthusen, H., Bergmann, A.: Investigations and measures to improve the acoustic characteristics of the German-Dutch Wind Tunnel DNW-LLF. In: \(18^{th}\) AIAA/CEAS Aeroacoustics Conference, Colorado Springs, Colorado (2012)Google Scholar
  13. 13.
    Jensen, H.W.: Realistic Image Synthesis Using Photon Mapping. A.K. Peters Ltd, Natick (2001) (ISBN 1568811470) Google Scholar
  14. 14.
    Jensen, H.W., Christensen, N.J.: Photon maps in bidirectional Monte Carlo ray tracing of complex objects. Comput Graph 19(2), 215–224 (1995)CrossRefGoogle Scholar
  15. 15.
    Martin, R.M., Brooks, T.F., Hoad, D.R.: Reduction of background noise induced by wind tunnel jet exit vanes. AIAA J 23(10), 1631–1632 (1985)CrossRefGoogle Scholar
  16. 16.
    Melber-Wilkending, S., Bergmann, A.: Aeroacoustic optimization of the NWB airline and turning vanes based on high fidelity CFD and acoustic simulation. In: \(18^{th}\) AIAA/CEAS Aeroacoustics Conference, Colorado Springs, Colorado (2012)Google Scholar
  17. 17.
    Moreau, A., Enghardt, L.: A first step towards a parametric model for fan broadband and tonal noise. In: Proceedings of the DAGA Conference, Dresden, Germany (2008)Google Scholar
  18. 18.
    Moreau, A., Gurin, S.: Development and application of a new procedure for fan noise prediction. In: \(16^{th}\) AIAA/CEAS Aeroacoustics Conference, Stockholm (2010)Google Scholar
  19. 19.
    Moreau, A., Gurin, S.: Similarities of the free-field and in-duct formulations in rotor noise problems. \(17^{th}\) AIAA/CEAS Aeroacoustics Conference, Portland, Oregon (2011)Google Scholar
  20. 20.
    Nishimura, M., Kudo, T., Nishioka, T.: Aerodynamic noise reducing techniques by using pile-fabrics. In: \(5^{th}\) AIAA/CEAS Aeroacoustics Conference, Bellevue, WA (1999)Google Scholar
  21. 21.
    Paidoussis, M.P.: Flow-induced vibrations in nuclear reactors and heat-exchangers. In: Naudasher, E., Rockwell, D. (eds.) Practical Experiences with Flow-Induced Vibrations. Springer, New York (1980)Google Scholar
  22. 22.
    Papenfuss, H.D. et al.: Lowering the turbulence level in an open-jet wind tunnel by novel adjustable jet-exit vanes. In: FVP Symposium on Aerodynamics of Wind Tunnel Circuits and their Components, CP-585, Moscow (1996)Google Scholar
  23. 23.
    Parker, R.: Resonance effects in wake shedding from parallel plates: some experimental observations. J. Sound Vib. 5(2), 330–343 (1966)CrossRefGoogle Scholar
  24. 24.
    Parker, R.: Resonance effects in wake shedding from parallel plates: calculation of resonant frequencies. J. Sound Vib. 5(2) (1967)Google Scholar
  25. 25.
    Pott-Pollenske, M., von Heesen, W., Bergmann, A.: Acoustic pre-examination work and characterization of the low-noise wind tunnel DNW-NWB. In: \(18^{th}\) AIAA/CEAS Aeroacoustics Conference, Colorado Springs, Colorado (2012)Google Scholar
  26. 26.
    Remillieux, M.C., Crede, E.D., Camargo, H.E., Burdisso, R.A., Devenport, W.J., Rasnick, M., Van Seeters, P., Chou, A.: Calibration and demonstration of the new Virginia Tech anechoic wind tunnel. In: \(14^{th}\) AIAA/CEAS Aeroacoustics Conference, Vancouver, British Columbia Canada (2008)Google Scholar
  27. 27.
    Roeber, N., Andres, S., Masuch, M.: HRTF simulations through acoustic Raytracing, Tech. Rep., Fakultaet fuer Informatik, Otto-von-Guericke Universitaet Magdeburg (2006)Google Scholar
  28. 28.
    Roeber, N., Kaminski, U., Masuch, M.: Ray acoustics using computer graphics technology. In: Proceedings of the \(10^{th}\) International Conference on Digital Audio Effects, Bordeaux (2007)Google Scholar
  29. 29.
    Schneider, S., Wiedemann, J., Wickern, G.: Das Audi-Windkanalzentrum, Aerodynamik des Kraftfahrzeugs, Haus der Technik, Essen, Germany (1998)Google Scholar
  30. 30.
    Seiferth, R.: Vorausberechnung und Beseitigung der Schwingungen von Freistrahl-Windkanlen, Aerodynamische Versuchsanstalt, Goettingen, Germany (1946)Google Scholar
  31. 31.
    Sijtsma, P.: CLEAN based on spatial source coherence. Int. J. Aeroacoust. 16(4), 357–374 (2007)CrossRefGoogle Scholar
  32. 32.
    Sijtsma, P., Merino-Martinez, R., Malgoezar, A., Snellen, M.: High-resolution CLEAN-SC: theory and experimental validation. Int. J. Aeroacoust. 16(4–5), 274–298 (2017)CrossRefGoogle Scholar
  33. 33.
    Voss, C., Becker, K., Lawerenz, M.: Multi-objective optimization in axial compressor design using a linked CFD-Solver, In: ASME Turbo Expo 2008 Conference (2008)Google Scholar
  34. 34.
    von Heesen, W.: Abnormal high-level tonal noise in axial-flow fans. In: \(4^{th}\) AIAA/CEAS Aeroacoustics Conference, Toulouse (1998)Google Scholar
  35. 35.
    Waudby-Smith, P., Ramakrishnan, R.: Wind tunnel resonances and Helmholtz resonators. Can. Acoust. 35(1), 3–11 (2007)Google Scholar
  36. 36.
    Welsh, M.C., Stokes, A.N., Parker, R.: Flow-resonant sound interaction in a duct containing a plate—Part I: semi-circular leading edge. J. Sound Vib. 95(3), 305–323 (1984)CrossRefGoogle Scholar
  37. 37.
    Wickern, G., von Heesen, W., Wallmann, S.: Wind tunnel pulsations and their active suppression. SAE Technical Paper 2000-01-0869 (2000)Google Scholar
  38. 38.
    Woodward, R., Hughes, C., Berton, J.: Benefits of swept and leaned stators for fan noise reduction. In: \(37^{th}\) Aerospace Sciences Meeting, Reno, Nevada (1999)Google Scholar
  39. 39.
    Woodward, R., Hughes, C., Jeracki, R., Miller, C.: Fan noise source diagnostic test: Far-field acoustic results. In: \(8^{th}\) AIAA/CEAS Aeroacoustics Conference, Breckenridge, Colorado (2002) International standards:Google Scholar

International standards

  1. 40.
    ISO 9613-1:1993: Attenuation of sound during propagation outdoors—Part 1: calculation of the absorption of sound by the atmosphere. International Organization for Standardization (1993)Google Scholar
  2. 41.
    ISO 266:2003: Normal equal-loudness-level contours. International Organization for Standardization (2003)Google Scholar
  3. 42.
    ISO 15186-2:2003: Measurement of sound insulation in buildings and of building elements using sound intensity—Part 2: field measurements. International Organization for Standardization (2003)Google Scholar
  4. 43.
    ISO 18233:2006: Application of new measurement methods in building and room acoustics. International Organization for Standardization (2006)Google Scholar
  5. 44.
    ISO 3745:2012: Determination of sound power levels and sound energy levels of noise sources using sound pressure—precision methods for anechoic rooms and hemi-anechoic rooms. International Organization for Standardization (2012)Google Scholar
  6. 45.
    ISO 717-1:2013: Rating of sound insulation in buildings and of building elements—Part 1: airborne sound insulation. International Organization for Standardization (2013)Google Scholar

Copyright information

© Deutsches Zentrum für Luft- und Raumfahrt e.V. 2019

Authors and Affiliations

  1. 1.German-Dutch Wind Tunnels (DNW)BraunschweigGermany
  2. 2.German-Dutch Wind Tunnels (DNW)MarknesseThe Netherlands

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