Leonardo I4N research program – design of novel acoustic liners for aero engine nacelles

Abstract. The minimisation of aircraft noise remains a major challenge for the aerospace industry. Noise certification limits continue to be driven lower over time to counter the impact of the steadily increasing number of noise events in the vicinity of airports, along with an increased sensitivity of the public to aircraft noise. This, in turn, ensures that considerable engineering time and effort is used to target all of the major contributors to aircraft noise. Aircraft noise sources include engine fan inlet, fan bypass, jet, and airframe noise, among others. Fan inlet, bypass, and core, ducts are typically lined with absorbing acoustic panels in order to minimise radiated fan noise. This paper is focussed on the latter, describing work to address the design and optimisation of novel acoustic liners.