Optimisation of non-locally reacting liners for improved duct attenuation

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

“…However, they may not be used in aero engines given their propensity to retain fluids. In this work [2], a set of parametric studies were also performed to look at the acoustic attenuation of nonlocally reacting liners which are also suitable to fly within aero engine ducts.…”

“…The studies have led to the development of a number of low weight novel liner configurations of varying complexity which are predicted to show improved broadband attenuation when compared to that realised for traditional designs. Work has included the development and validation of acoustic liner impedance models [1], liners with porous cell walls and cells which are considerably wider than traditional designs [2], and the design and manufacture of novel liners with complex cavities (replacing traditional straight cavities) [3,4]. The attenuation potential of the novel designs is improved further by increasing the integrity of duct liner attenuation modelling Materials Research Proceedings 37 (2023) 6-9 https://doi.org/10.21741/9781644902813-2 7 significantly, in particular by using a more representative source content and by including the influence of boundary layer refraction at the duct walls [5].…”