Research carried out at University of Limerick (UL) will play a major part in reducing aircraft noise and emissions in the future. UL researchers Dr Trevor Young and Dr Aidan Cloonan, Irish Centre for Composites Research (IComp) and the Materials and Surface Science Institute (MSSI) at UL, are collaborating on a major European research programme, “Clean Sky Sustainable and Green Engines” (SAGE) integrated technology development programme, dedicated to demonstrating new engine technologies for a range of future civil aerospace applications. The European Commission’s Clean Sky research programme aims to "green" the aviation sector in line with Advisory Council for Aeronautics Research in Europe (ACARE) targets. These targets require the industry to cut carbon dioxide emissions by 50%, nitrogen oxide emissions by 80% and external noise by 50%.
In a significant milestone for the SAGE programme, Bombardier Belfast has recently designed and manufactured a large one-piece composite engine nacelle component, namely a carbon fibre composite intake acoustic liner, which encases and attenuates the noise of large turbofan aircraft engines.
UL was responsible for material testing and analysis of candidate materials for the exposed inner surface of the acoustic liner barrel. This involved fatigue testing, accelerated rain droplet and particle erosion testing and accelerated weathering testing.
Commenting on the achievement, Colin Elliot, Vice-President of Engineering and Product Development at Bombardier Belfast, said: “An intake liner is usually manufactured in two or three curved segments which are assembled to longitudinal splices. But with zero splice, one-piece design, you get a much better noise attenuation, as you are able to apply an uninterrupted acoustic treatment to the liner, which has the potential to reduce noise. Additional potential benefits to a customer of a splice-less intake acoustic liner include a reduction in weight, and reduced maintenance and repairs.”
Dr. Trevor Young, University of Limerick, explains: “the manufacture of acoustic liners from carbon fibre composites material presents a host of new challenges. New technologies for the drilling of thousands of small holes had to be developed. It was also important to develop an understanding of how the material would behave during a lifetime of service. To this end accelerated erosion and weathering testing is critical.”
The full-scale intake liner, assembled to a one-piece lipskin, was formally handed over to Rolls-Royce to support its composite fan demonstration programme. The intake liner will be assembled to the Advanced Low Pressure System (ALPS) demonstrator engine being developed at Rolls-Royce’s facility in Derby, prior to ground testing.
SAGE comprises six separate research streams dedicated to demonstrating new engine technologies for a range of future civil aerospace applications. Bombardier Belfast, which has significant expertise in nacelle technology development, has been leading a €3.75 million project within SAGE3, known as SAGE3 ALTD (Intake Acoustic Liner Technology Development), with research partners the Irish Centre for Composites Research at the University of Limerick and the Institute of Sound and Vibration Research, University of Southampton.