Predicting and reducing aircraft noise

Air travel in the UK has increased five-fold over the last 30 years. Half the population now flies at least once a year and freight traffic at UK airports has doubled since 1990. Similar statistics hold for other developed countries. It is likely that this growth will be eclipsed in the years to come by the expansion in civil aviation within emerging giants such as India and China. Civil aviation links distant communities for social and business purposes and gives affordable access to foreign travel for leisure purposes. It is unlikely however that the global community can continue to enjoy the benefits of air travel through increased capacity regardless of environmental cost. To tackle this problem, a balanced approach is essential which recognises the importance of air travel, but which also deals with environmental issues such as noise and emissions. Predicting the effects of noise and emissions is a first essential step towards such a solution. This article focuses on the prediction of aircraft noise and on developing noise reduction technologies. The aircraft noise issue is that of reducing the environmental impact of exterior noise at take-off and approach. This constitutes a major nuisance to residents near airports. It has resulted in stringent local airport regulations, such as the ‘quota count’ system at Heathrow, which are now more restrictive in defining acceptable limits for aircraft noise than are the international noise regulations promulgated by ICAO which first brought aircraft noise within a regulatory framework in the sixties and seventies. In this article, the major sources of noise in a modern aircraft are discussed, and current techniques for predicting aircraft noise are reviewed. These include the effects of source definition and acoustic treatment. Recent advances in noise reduction technology will be presented and their performance assessed in the light of noise targets set by the Advisory Council for Aeronautics Research in Europe (ACARE) in their ‘vision 2010’ and ‘vision 2020’ plans. Finally some specific noise reduction technologies will be described which have been developed and assessed in recent EC projects.

[1]  Anurag Agarwal,et al.  Low-Frequency Acoustic Shielding by the Silent Aircraft Airframe , 2007 .

[2]  Zhaokai Ma,et al.  Attenuation of Slat Trailing Edge Noise Using Acoustic Liners , 2006 .

[3]  H. Ribner,et al.  Shielding concepts for jet noise , 1981 .

[4]  Malcolm Smith,et al.  Validation of a prediction model for aerodynamic noise from aircraft landing gear , 2002 .

[5]  Jean-François Remacle,et al.  Efficient Discontinuous Galerkin Methods for solving acoustic problems , 2005 .

[6]  R. J. Astley,et al.  Modelling tone propagation from turbofan inlets: the effect of extended lip liners , 2002 .

[7]  W Ganz Ulrich,et al.  Boeing 18-Inch Fan Rig Broadband Noise Test , 1998 .

[8]  Philip A. Nelson,et al.  Sound source characterisation: the focussed beamformer and the inverse method , 2003 .

[9]  Werner Dobrzynski,et al.  Prediction of low noise aircraft landing gears and comparison with test results , 2006 .

[10]  R. Jeremy Astley,et al.  Validation and Application of a Hybrid Prediction Scheme for Bypass Duct Noise , 2006 .

[11]  Renaud Davy,et al.  Flight Test Investigation of Add-On Treatments to Reduce Aircraft Airframe Noise , 2005 .

[12]  S. Lele,et al.  Current Status of Jet Noise Predictions Using Large-Eddy Simulation , 2008 .

[13]  Philip A. Nelson,et al.  A numerical method for computation of sound radiation from an unflanged duct , 2004 .

[14]  Fabienne Montetagaud,et al.  Negatively Scarfed Intake: Design and Acoustic Performances , 2005 .

[15]  Alessandro Bassetti,et al.  A RANS Based Jet Noise Prediction Scheme , 2003 .

[16]  Philip J. Morris,et al.  Prediction of Fan Exhaust Noise Propagation , 2005 .

[17]  Naoki Tsuchiya,et al.  Low Noise FEGV Designed by Numerical Method Based on CFD , 2004 .

[18]  Mehdi R. Khorrami,et al.  Time-Accurate Simulations and Acoustic Analysis of Slat Free Shear Layer , 2002 .

[19]  Daniel L. Sutliff,et al.  Low-Speed Fan Noise Reduction with Trailing EDGE Blowing , 2002 .

[20]  R. J. Astley,et al.  The partition of unity finite element method for short wave acoustic propagation on non‐uniform potential flows , 2006 .

[21]  R. J. Astley,et al.  Acoustic scattering by an axially-segmented turbofan inlet duct liner at supersonic fan speeds , 2006 .

[22]  Naoki Tsuchiya,et al.  Finite element models for predicting the propagation and radiation of fan noise from turbofan engines , 2006 .

[23]  Renaud Davy,et al.  ROSAS Wind Tunnel Test Campaign Dedicated to Unconventional Aircraft Concepts Study , 2004 .

[24]  Simon Richards,et al.  Parallel Computation of 3D Acoustic Radiation from an Engine Intake , 2005 .

[25]  Carl H. Gerhold,et al.  Inlet Noise Reduction by Shielding for the Blended-Wing-Body Airplane , 1999 .

[26]  F. Farassat,et al.  Aircraft Engine Noise Scattering By Fuselage and Wings: A Computational Approach , 2003 .

[27]  C. Tam,et al.  Dispersion-relation-preserving finite difference schemes for computational acoustics , 1993 .

[28]  R. J. Astley,et al.  Prediction methods for propagation in bypass ducts and comparison with measured data , 2005 .

[29]  E Campos.  Aeroacoustics research in Europe: the CEAS-ASC report on 2002 highlights , 2003 .

[30]  Werner Dobrzynski,et al.  Design and Testing of Low Noise Landing Gears , 2005 .

[31]  Walter Eversman.  Mapped Infinite Wave Envelope Elements for Acoustic Radiation in a Uniformly Moving Medium , 1999 .

[32]  Yueping Guo,et al.  A statistical model for landing gear noise prediction , 2003 .

[33]  T. G. Sofrin,et al.  Axial Flow Compressor Noise Studies , 1962 .

[34]  H. Siller,et al.  Novel Methods for Acoustic Indoor Measurements and Applications in Aero-Engine Test Cells , 2006 .

[35]  Kenji Takeda,et al.  Computational aeroacoustic simulations of leading-edge slat flow , 2004 .

[36]  Harvey H. Hubbard,et al.  Aeroacoustics of Flight Vehicles: Theory and Practice. Volume 1: Noise Sources , 1991 .

[37]  Mark H. Dunn,et al.  Investigation of acoustical shielding by a wedge-shaped airframe , 2006 .

[38]  N.W.M. Ko,et al.  The initial region of subsonic coaxial jets , 1976, Journal of Fluid Mechanics.

[39]  Michael Fisher,et al.  A modeling of the noise from simple co-axial jets , 1993 .

[40]  P. A. Lush,et al.  Measurements of subsonic jet noise and comparison with theory , 1971, Journal of Fluid Mechanics.

[41]  M. Lighthill.  On sound generated aerodynamically I. General theory , 1952, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[42]  Andy J. Keane,et al.  Response Surface Method Optimization of Uniform and Axially Segmented Duct Acoustics Liners , 2006 .

[43]  K. Taylor.  A transformation of the acoustic equation with implications for wind-tunnel and low-speed flight tests , 1978, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[44]  G. F. Homicz,et al.  A note on the radiative directivity patterns of duct acoustic modes , 1975 .

[45]  R. J. Astley,et al.  A Computational Mode Matching Approach for Propagation in Three-Dimensional Ducts with Flow , 2006 .

[46]  Anurag Agarwal,et al.  Ray tracing approach to calculate acoustic shielding by a flying wing airframe , 2007 .

[47]  Hugues Remy,et al.  Landing Gears and High Lift Devices Airframe Noise Research , 2002 .

[48]  Alan McAlpine,et al.  Finite/boundary element assessment of a turbofan spliced intake liner at supersonic fan operating conditions , 2003 .

[49]  R. J. Astley,et al.  Modelling of flow effects on propagation and radiation from bypass ducts , 2005 .

[50]  Nick J. Baker,et al.  Scattering of Sound by Liner Splices: A Kirchhoff Model with Numerical Verification , 2006 .

[51]  Philip J. Morris,et al.  The Prediction of Jet Noise From CFD Data , 2004 .

[52]  J. A. Fitzpatrick,et al.  Aeroacoustics research in Europe: The CEAS-ASC report on 2004 highlights , 2005 .

[53]  Mark Drela,et al.  Airframe Design for "Silent Aircraft" , 2007 .

[54]  Damiano Casalino,et al.  A rod-airfoil experiment as a benchmark for broadband noise modeling , 2005 .

[55]  P. Morris,et al.  Calculation of sound propagation in nonuniform flows: Suppression of instability waves , 2004 .