Development of acoustic liner in aero engine: a review

Ma, Xiaofeng; Zheng-tao, SU

doi:10.1007/s11431-019-1501-3

Cited by 40 publications

(18 citation statements)

References 85 publications

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“…The minimisation of the objective functions is achieved through a Particle Swarm Optimization (PSO) algorithm, using a swarm with ten individuals per variable. In the proposed approach, the optimisation variables are the equivalent lengths of the cells h i , bounded allowing a range of ∆φ of 2π for each cell, see Equation (3). The bulk modulus and the inertia tensor of each metafluid cell are then evaluated with Equation (9).…”

Section: Resultsmentioning

confidence: 99%

“…Huge research has been conducted on low noise technologies for engine components to alleviate the aviation-related community noise, e.g., the acoustic liners that extensively cover the inner surfaces of modern turbofan nacelles, being the single-degree-of-freedom liners particularly effective for tonal noise abatement [3], acting on one of the primary sources on aircraft. The evolution of turbofans, however, is leading towards a further increase of the bypass ratio and fan diameters, as confirmed by the comparison between CFM International Leap and CFM-56 or the General Electric GE9x with GE90.…”

Section: Introductionmentioning

confidence: 99%

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Innovative Acoustic Treatments of Nacelle Intakes Based on Optimised Metamaterials

et al. 2021

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Modern turbofans with high bypass ratios, low blade passage frequencies and short nacelles require continuous development of acoustic linings to achieve the noise reductions expected by the international aviation authorities. Metamaterials and metafluids have been recently proposed as promising technologies for designing innovative acoustic treatments dedicated to reducing aeronautic turbofan noise emissions. In this work, a phase-gradient metasurface treatment is investigated as a way to tackle the noise radiation from an axially symmetric nacelle. This paper aims to study the potential benefits of the mentioned technology, and is not an attempt to design a complete new liner or nacelle. The metasurface is modelled through an equivalent metafluid, and a simulation-based optimisation is used in defining the design parameters. The tonal contribution of the blade passage frequency is considered, and the numerical results with the metafluid optimised on one azimuthal mode at a time show a significant effect in terms of acoustic levels and directivity over an arc of virtual receivers.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Innovative Acoustic Treatments of Nacelle Intakes Based on Optimised Metamaterials

et al. 2021

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“…6). Each one covers an area of 10 Â 5 cm 2 , although the operating area is restricted to 7 Â 5 cm 2 . With such dimensions active control can be efficient up to approximately 2 kHz.…”

Section: Methodsmentioning

confidence: 99%

“…Recent aircraft engines developments have been focusing on decreasing the fan's rotation speed, with the aim of reducing their fuel consumption. Consequently, the frequencies of the tonal noise emitted with such architectures are lower than for previous engine generations [1,2]. Absorbing sound within this new frequency range would not be such a challenge if the space and the weight allocated to the acoustic treatment were not limited.…”

Section: Introductionmentioning

confidence: 99%

Corona discharge actuator as an active sound absorber under normal and oblique incidence

Sergeev¹,

Humbert

Lissek

et al. 2022

Acta Acust.

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In the majority of active sound absorbing systems, a conventional electrodynamic loudspeaker is used as a controlled source. However, particular situations may require an actuator that is more resistant to harsh environments, adjustable in shape, and lighter. In this work, a plasma-based electroacoustic actuator operating on the atmospheric corona discharge principle is used to achieve sound absorption in real-time. Two control strategies are introduced and tested for both normal in the impedance tube and grazing incidence in the flow duct. The performance of plasma-based active absorber is competitive with conventional passive technologies in terms of effective absorption bandwidth and low-frequency operation, however, it presents some inherent limitations that are discussed. The study reveals that the corona discharge technology is suitable for active noise control in ducts while offering flexibility in design, compactness, and versatility of the absorption frequency range.

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“…Hence, the sound field due to rotating sources in turbomachines is of great interest, especially, in terms of sound absorbers. The calculation of the sound field and the acoustic energy flow may help to develop and to improve the acoustic absorption performance of micro-perforated duct absorber of axial fans [1][2][3] and acoustic liners, which were integrated into the casing around an aircraft engine [4,5]. For those absorbers, the best absorption performance is obtained if the angle of the acoustic intensity vector corresponds to the normal direction of the absorbing surface.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional acoustic energy flow from rotating sound sources

Ocker

Pannert

2021

Acta Acust.

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A detailed study of the three-dimensional sound fields around a monopole point source in subsonic and supersonic rotation is investigated. We calculate the sound pressure, the acoustic velocity, as well as the instantaneous and time-averaged acoustic intensity fields with the advanced time approach. The advanced time approach is applied for sound sources at subsonic and supersonic rotation and yield comparable results as those obtained from the spherical harmonic series expansion method or the solution of the retarded time equation. Further, the direction of the time-averaged acoustic energy flow is derived from the acoustic intensity vectors. It is shown, that the direction of the energy flow path differs from the radial direction and depends on the rotational direction and rotational velocity. Those findings are useful, for example, to improve the acoustic absorption performance of sound absorbers and acoustic liners around turbomachines.

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Development of acoustic liner in aero engine: a review

Cited by 40 publications

References 85 publications

Innovative Acoustic Treatments of Nacelle Intakes Based on Optimised Metamaterials

Innovative Acoustic Treatments of Nacelle Intakes Based on Optimised Metamaterials

Corona discharge actuator as an active sound absorber under normal and oblique incidence

Three-dimensional acoustic energy flow from rotating sound sources

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