Smart Acoustic Lining for UHBR Technologies Engine Part 2: acoustic treatment at the intake of a scaled turbofan nacelle

TL;DR

This paper presents the development and testing of electro-active acoustic liners for UHBR turbofan engine intakes, aiming to reduce low-frequency noise with adaptable surface impedance in constrained nacelle spaces.

Contribution

It introduces electro-active liners with programmable impedance for turbofan nacelle intake noise reduction, advancing from TRL 3-4 in a scaled test setup.

Findings

Electro-active liners show potential for noise reduction in scaled turbofan models.

The technology can adapt boundary conditions to improve acoustic treatment.

Performance demonstrates feasibility for future full-scale applications.

Abstract

The new generation of Ultra-High-By-Pass-Ratio (UHBR) turbofan engine while considerably reducing fuel consumption, threatens higher noise levels at low frequencies because of its larger diameter, lower number of blades and rotational speed. This is accompanied by a shorter nacelle, leaving less available space for acoustic treatments. In this context, a progress in the liner technology is highly demanded, prospecting alternative solutions to classic liners. The SALUTE H2020 project has taken up this challenge, proposing electro-active acoustic liners, made up of loudspeakers (actuators) and microphones (sensors). The electro-active means allow to program the surface impedance on the electroacoustic liner, but also to conceive alternative boundary laws. Test-rigs of gradually increasing complexities have allowed to raise the Technology Readiness Level (TRL) up to 3-4. In this second part, the electroacoustic liner is adapted to treat the walls at the intake of a scaled turbofan nacelle. The performance of the electroacoustic liner demonstrate its potentialities for reducing noise radiation from turbofan.