Hybrid Innovative Boundary Operators for Noise Treatment Evolution: application to duct acoustics

Objective

Aircraft noise has huge health and economic impacts, and the EU targets 65% of noise reduction by 2050. Meanwhile, restrictions in fuel consumption led to the Ultra-High-Bypass-Ratio turbofans, whose low-frequency noise signature challenges the scientific community. HiBONTE takes up this challenge, by designing innovative boundary noise control combining the most advanced know-hows on active and passive approaches. HiBONTE is the natural evolution of SmartAnswer MSCA-ITN (ESR12 task) and SALUTE H2020, both directed by the Ecole Centrale de Lyon (ECL), and the national project DAMA directed by the Università degli Studi di Napoli (UNINA). In ECL, an acoustic liner made of Electroacoustic Resonators (ERs) has been validated against turbofan noise. However, while efficient and tunable at low frequencies, high-frequencies are prevented by stability issues. Meanwhile, in UNINA, several passive concepts have been investigated, arriving at the conclusion that multistructured acoustic metamaterials (AM) hybridizing different noise control concepts, can improve global performances. However, AM, as all passive approaches, cannot escape the integral constraint requiring larger thickness at low frequencies. The need of hybridizing ERs and AM for broadband and tunable noise control, is evident, and times are mature to face this unprecedented challenge. HiBONTE will conceive an innovative boundary operator to be synthesized, for the first time, by a hybrid liner, which will be tested on highly representative testbenches in UNINA and ECL. Training activities will support each stage, and a unique multimodal flow-duct facility will be created in UNINA. The outcomes of HiBONTE are expected to be exploited by industrial stakeholders of both aircraft engines and Heating and Ventilation Air-Conditioning Systems, allowing to achieve the noise pollution reduction policies prescribed by the EU. Moreover, HiBONTE will prompt my career towards future grants and permanent academic positions.