Turbomachinery noise radiation through the engine exhaust

[ go to the project website ]


  • In-Duct and Far-Field Mode Detection Techniques
  • Aft fan noise reduction with a lined afterbody
  • Acoustic Near- to Far-field Characteristics of Nozzle Radiation Through Plug Flow Jets 

[ go to publication index]


TURNEX has delivered validated industry-exploitable methods for predicting turbomachinery noise radiation through exhaust nozzles, which will allow EU industry to compete effectively with NASA-funded technology developments in the US. It has also delivered a technical assessment on the way forward for European fan noise testing facilities and an assessment of exhaust nozzle concepts for noise reduction at source.

TURNEX has addressed technical domain 2.f (External noise) of area 2 (Improving environmental impact with regard to emissions and noise) for Priority Thematic Area 4 (Aeronautics and Space) of the Specific Programme ‘Integrating and strengthening the European Research Area’. It supports the EU FP6 objective of reducing aircraft external noise by 4-5 dB and by 10 dB per operation in the short and long-term respectively

Research is needed to develop innovative concepts and enabling technologies to reduce aero engine noise at source. Turbomachinery noise radiating from the bypass and core nozzles is becoming a dominant noise source on modern aircraft, but, while recent EU research programmes have made significant progress in reducing both the generation of turbomachinery noise and the radiation of noise from the intake, little work has been conducted on reducing the radiation of turbomachinery noise from exhaust nozzles. TURNEX has addressed this shortfall by delivering improved understanding and validated design methods, and by evaluating a number of low-noise exhaust nozzle configurations aimed at a source noise reduction of 2-3dB.

The goal of TURNEX was to develop concepts and enabling technologies for reduction of engine noise at the source, through an improved understanding, modelling and prediction of fan and turbine noise radiation from exhaust nozzles, and through the evaluation of a number of low-noise exhaust nozzle configurations. To achieve that goal, TURNEX had four focussed, ambitious objectives.

1. To test experimentally at model scale (a) innovative noise reduction concepts, including a scarfed exhaust nozzle, and (b) conventional engine exhaust configurations. The experiments will develop and utilise novel simulated turbomachinery noise sources and innovative measurement techniques in order to evaluate the noise reduction concepts and to provide a high quality validation database.

2. To improve models and prediction methods for turbomachinery noise radiation through the engine exhaust to a level comparable with that being achieved for intake radiation, to address specific shortcomings associated with such methods, and to validate those methods with the experimental data.

3. To conduct a parametric study of real geometry/flow effects (pylons, wings, flow-asymmetry) and noise reduction concepts (scarfed nozzles, acoustically lined after-body and wing) as applied to current and future aircraft configurations of interest, aimed at achieving a 2-3dB source noise reduction.

4. To assess technically the relative merits of different methods of estimating far-field noise levels from in-duct and near-field noise measurements, using both models and the validation data, in order to enhance the capability of European fan noise test facilities to investigate and simulate fan noise radiation through the exhaust.

The consortium consisted of two leading airframe manufacturers, three leading engine manufacturers, an SME that specialises in computational aeroacoustics software, three leading research centres and three leading universities from France, Germany, Belgium, the Netherlands, Italy, Turkey and the UK. This mix of partners has formed the basis for delivering the ambitious project objectives.


Publishable Final Activity Report



Project Coordinator


  • Free Field Technologies (BE)
  • Rolls-Royce (DE)
  • Middle East Technical University  (TR)
  • Technische Universitait Eindhoven (NL)
  • Dassault Aviation     (FR)
  • Avio SPA (IT)
  • Rolls-Royce (UK)
  • Deutsches Zentrum fuer Luft und Raumfahrt E.V. (DE)
  • Stichting Nationaal Lucht en Ruimtevaart Laboratorium (NL)
  • Airbus (FR)

Project status

Start Date : 2005-01-01
End Date : 2007-12-31
Duration : 36 months
Project Status : Completed
Programme Type : 6th FWP (Sixth Framework Programme)