Model-inversion control to enforce tunable Duffing-like acoustical response on an Electroacoustic resonator at low excitation levels

In the aim of attenuating noise transmission through air-ducts, research is prompted for overcoming the limitations of classical acoustic liners, especially in the aero-engines applications. The new generation of Ultra-High-By-Pass-Ratio (UHBR) turbofans while considerably reducing fuel consumption, increases noise pollution especially at lower frequencies because of their larger diameter, lower number of blades and rotational speed. Moreover, they present a shorter nacelle, leaving less available space for acoustic treatments. In case of simplified one-dimensional propagation, integral constraints exist which analytically define the limits of the scattering performances of reciprocal systems, such they are the local impedance liners, for a fixed length of the acoustic treatment along the duct. In this contribution, we analyse a special boundary condition breaking the reciprocity principle, and overcoming the limitations of locally reacting liners. We call it Advection Boundary Law as it introduces a convection on the boundary, responsible of non-reciprocal behaviour at grazing incidence, and of the enhancement of transmission loss with respect to pure locally-reacting resonators. Performances and passivity of such boundary law are numerically analysed first in grazing-incidence problems. The grazing-incidence problem is experimentally studied in a plane-wave acoustic waveguide lined by electroacoustic resonators which can be programmed to reproduce such advection boundary law.

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The Advection Boundary Law in presence of mean-flow and spinning modes

De Bono,

Collet,

Ouisse

et al. 2024

Active and Passive Smart Structures and Integrated Systems XVIII

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In the attempt to reduce fuel consumption, a new generation of Ultra-High-By-Pass-Ratio (UHBR) turbofans have been introduced in the aeronautic industry which are structurally noisier especially at lower frequencies, because of their larger diameter, lower number of blades and rotational speed. Moreover, they present a shorter nacelle, leaving less available space for acoustic treatments. For this reason, innovation in the liner technology is highly demanded. In this contribution, we analyse the performances of an electroacoustic liner, made up of microphones (sensors) and small loudspeakers (actuators). Such array of electroacoustic resonators can feature an interesting boundary operator, called Advection Boundary Law. Such boundary law has been analysed in grazing-incident acoustic fields without air-flow and in case of plane waves. Here, we adapt such boundary condition to attenuate spinning modes. Numerical simulations in case of spinning-modes, shows the potentiality and the passivity issues of such innovative boundary law. Finally, a reproduction of a turbofan engine (scale 1:3) accomplishing real-life rotational speeds, allows to assess the performances of the Advection Boundary Law in presence of mean-flow and spinning-modes.

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Model-inversion control to enforce tunable Duffing-like acoustical response on an Electroacoustic resonator at low excitation levels

Cited by 6 publications

References 29 publications

Stochastic optimization of targeted energy transfer with time-dependent cubic nonlinearity

Stochastic optimization of targeted energy transfer with time-dependent cubic nonlinearity

Breaking the limitations of local impedance noise control: passivity, and scattering performances of the Advection Boundary Law

The Advection Boundary Law in presence of mean-flow and spinning modes

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