Bombardier Belfast has designed and manufactured a full-scale novel one-piece carbon fiber reinforced plastic (CFRP) engine intake acoustic liner, and achieved a significant milestone in the Clean Sky Sustainable and Green Engines (SAGE) integrated technology demonstrator program, aimed at further reducing aircraft emissions and noise.
SAGE comprises six separate research streams dedicated to demonstrating new engine technologies for a range of future civil aerospace applications. Bombardier Belfast (Belfast, Ireland) has significant expertise in nacelle technology development, and has been leading a €3.75 million project within SAGE3, known as Clean Sky SAGE3 ALTD (Intake Acoustic Liner Technology Development). SAGE3 focuses on developing advanced low weight and low noise nacelle component technologies for large turbofan engines.
Intake acoustic liners encase large turbofan aircraft engines and attenuate their noise. Bombardier Belfast’s innovative new variant will support Rolls-Royce’s composite fan demonstration program. “An intake liner is usually manufactured in two or three curved segments which are assembled to longitudinal splices,” explained Bombardier Belfast VP of engineering and product development Colin Elliott. “But with a 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 spliceless intake acoustic liner include a reduction in weight, and reduced maintenance and repairs.”
Bombardier also successfully assembled a one-piece CFRP lipskin to the intake liner. The lipskin was produced by composite specialist EAST-4D (Dresden, Germany). Elliott commented, “From a manufacturing perspective, the process we used to create the splice-less liner involved developing very complex tooling, which was integral to the zero splice design, and which has resulted in a reduced manufacturing cycle time. We are delighted to have produced a full-scale demonstrator of this nature.”
The full-scale intake liner with lipskin was formally handed over to Rolls-Royce at a small ceremony in Bombardier’s nacelle facility in Newtownabbey, Northern Ireland. It will be assembled to the Advanced Low Pressure System (ALPS) demonstrator engine being developed at Rolls-Royce’s Derby, UK facility, prior to ground testing.
The University of Limerick (UL, Limerick, Ireland) 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.
UL professor Trevor Young explains: “the manufacture of acoustic liners from carbon fiber 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.”