RHAPSODI: A Ring of HAPS for active noise control of turbofan noise

Since 1997, Philippe Micheau has been a professor of mechatronics in the Department of Mechanical Engineering at the Université de Sherbrooke (UdeS, Quebec, Canada). His research focuses primarily on mechatronics applied to acoustics and on total liquid ventilation. Since 2020, he has been the director of the Centre de Recherche Acoustique-Signal-Humain (CRASH-UdeS).

Abstract: Active noise control (ANC) is well established through widely successful products such as active noise-cancelling headphones. However, multichannel active control remains an open research area, including the active control of turbofan noise within engine nacelles. The RHAPSODI project was initially motivated by the challenge of actively attenuating the intense tonal noise radiated by the fan. The main challenges are related to deploying a large number of secondary sources and microphones in a harsh environment. The originality of the proposed approach lies in the use of Harmonic Acoustic Pneumatic Sources (HAPS), capable of generating high acoustic levels.

The first part of the presentation reviews the historical development of compressed-air loudspeakers, from the auxetophone to HAPS. It covers both theoretical aspects and experimental results, spanning frequencies from low frequencies (below 100 Hz) to ultrasound (above 10 kHz), in both no-flow conditions and in flows up to Mach 0.5.

The second part addresses active control using multiple HAPS. Each HAPS must be controlled in both amplitude and phase, despite its relatively slow dynamic response. The signals from error microphones located near the sources must be compensated for near-field effects. Experimental results in tonal active control demonstrate noise reductions on the order of 20 dB SPL, achieved using a ring of six HAPS without flow (130 dB SWL), and with three HAPS in an infinite duct with flow (Mach 0.5, up to 144 dB).

The final part discusses future perspectives of this work. The control strategy developed within RHAPSODI can be extended to broadband noise, as demonstrated by its recent application to active double-glazing systems using electrodynamic loudspeakers. Ongoing work aims to accelerate the dynamic response of HAPS to enable subband control. Future directions include extending these concepts toward active control of sound directivity in free field.

Le lundi 4 mai 2026 à 11h00 / Amphithéâtre François Canac, LMA

More information about the speaker :