SYstem Manufacturing and Product design tHrough cOmponent Noise technologY (SYMPHONY)

Lead Participant: Rolls-Royce plc

Abstract

SYstem Manufacturing and Product design tHrough cOmponent Noise technologY
To reduce aircraft noise around airports and allow air traffic to grow, sustained noise reduction programmes are required, supported by Industry, National and European Funding. In addition, noise within aircraft cabins is an issue for the comfort of passengers and crew. The work in SYMPHONY was primarily driven by the need to address the key noise challenges of a new 150-seater sector aircraft informed by the near-term ACARE environmental goals for 2015 and local noise restrictions and access to airports. In 2011, more ambitious longer term environmental goals were outlined in the European report Flightpath 2050, making the work in SYMPHONY an essential basis for future Partner competitiveness in aircraft noise.
To achieve significant reductions in aircraft noise, it is necessary to reduce the noise of all the aircraft and engine components that contribute significantly to the total noise signature. This is because noise sources add in a logarithmic manner, such that reducing just one component can result in only a small effect on the total noise. SYMPHONY therefore delivered design methods and technology to address many of the principal sources of aircraft noise. The specific noise sources addressed were identified by individual partner company aircraft noise prediction processes, taking an integrated system approach to select specific technologies which simultaneously work together to achieve the broader environmental targets for noise, NOx and sfc. These requirements are reflected in the UK Noise Technology Roadmaps which are agreed by industry and universities under the EnvTec, NTC and X-Noise national networks.
The SYMPHONY consortium, lead by aero-engine manufacturer Rolls-Royce, consisted of eight industrial and academic partners representing a major section of the UK aero-acoustics community. Airframe manufacturer Airbus UK led the low noise landing gear studies and additionally contributed to the installation studies. Bombardier (Shorts) and GKN brought to the collaboration their extensive experience as nacelle suppliers to the aircraft industry. QinetiQ is a world leader in consultancy for exhaust noise and cabin noise, and in addition tests took place in their anechoic Noise Test Facility (NTF) which is the key strategic UK Noise facility for the dominant aircraft exhaust and installations noise sources. Southampton University developed prediction methods for noise of specific components, and implemented methods in the whole-aircraft noise prediction design system. This university has contributed effectively to most of the UK and EU noise research programmes over the past decade in addition to its on-going collaboration with Rolls-Royce and Airbus. Cambridge University developed prediction methods for turbo-machinery tone noise and combustion noise; it has a long record of excellence for the design of turbo-machinery and combustion components. Loughborough University contributed to aerodynamic modelling of high-speed flows associated with engine bleed systems and brought some 20 years experience in modelling high speed flows and validation techniques.
A number of innovative low-noise technologies were investigated in SYMPHONY, including techniques for reducing bleed system noise by detailed design, for attenuating fan noise by exploiting mode scattering at liner discontinuities, for reducing landing gear noise by careful attention to elements of the design not previously investigated, and for reducing jet noise by designing 3D nozzles specifically aimed at reducing jet-wing interaction effects. The application of CFD and CAA to aircraft noise problems already stretches computational techniques to the limit, due to the technical complexity and extreme computer processing and memory requirements. In order to achieve the accuracy and noise frequency range required for product design, Southampton, Cambridge and Loughborough universities undertook further significant and innovative developments in SYMPHONY to allow multi-disciplinary design optimisation of noise and aerodynamics simultaneously, which is key to meeting the sfc, NOx and noise reduction targets.
SYMPHONY comprised four Work Packages. At component level WPs 1-3 exploit innovative computational and experimental techniques to provide insight into the different noise source mechanisms, to deliver low noise concepts and to develop new physically-based noise design models. These component noise contributions were then integrated in WP4 into an optimised aircraft design.
Dissemination of SYMPHONY results is through the EnvTec, NTC and X-Noise National Networks to inform the UK Noise Technology Roadmaps for the future programmes.

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