Reducing noise emissions is one of the main design targets driving the development of new aircraft engines and is therefore a key priority for the competitiveness of the aerospace sector. Ultra-high bypass ratios (UHBR) turbofan engines are expected to equip the next generation of aircraft to maximise efficiency. The noise generated by these engines will concern lower frequencies compared to existing engine technologies. Also, with a thinner nacelle, absorption performance is expected to drop at low frequencies. And with a shorter nacelle, less surface area will be available for acoustic treatments. UHBR engine technologies then represent significant challenges for the design of next-generation acoustic treatments.
The SALUTE project will tackle these challenges by developing a new acoustic liner technology based on arrays of small loudspeakers or passive membranes. This innovative approach is able to deliver excellent sound absorption at low frequencies while remaining sufficiently small to fit into thin nacelle geometries. This development will be carried out on three different concepts, which will be compared and down-selected in the course of the project. Conventionally, these acoustic treatments were tested using 2D (i.e. flat) prototypes, which will constitute a baseline configuration of the project.
The SALUTE project will go further by testing 3D prototypes with a geometry corresponding to a small-scale fan at the PHARE test facility. This is required to reach TRL4 but will present specific challenges in terms of manufacturing. Secondly, gaining more insight into the physical interaction between the transducers, the control system and the high-speed flow will be necessary. This will be achieved through multi-physics simulations coupling all these sub-systems. With four partners with proven track record of successful collaborative projects on the topic, the SALUTE project will benefit from the latest technological developments on smart acoustic liners.