On the integration of acoustic phase-gradient metasurfaces in aeronautics

Palma, Giorgio; Burghignoli, Lorenzo

doi:10.1177/1475472x20954404

Cited by 12 publications

(10 citation statements)

References 21 publications

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“…However, it can be found that most of the present optimizations for the acoustic metamaterial are based on theoretical modeling [ 20 , 21 , 22 ] or finite element simulation [ 23 , 24 ]. Gritsenko and Paoli [ 20 ] had proposed a novel theoretical approach to characterize bubble-based metamaterials based on the findings for a single bubble trapped in circular cavity modeled as a thin clamped plate and further conducted the theoretical optimization of the trapped-bubble-based acoustic metamaterial performance.…”

Section: Introductionmentioning

confidence: 99%

“…The receptance functions of metamaterial beams with various resonator connection architectures were derived by Wei et al [ 21 ] according to the transfer matrix model and further be verified through finite element model results. Palma and Burghignoli [ 22 ] had conducted the theoretical link between two widely used metamaterial models of transformation acoustics and generalized Snell’s Law, and it was exploited to perform an optimal design of phase-graded metasurface acoustic lining of a 2-D duct in presence of flow. Tang et al [ 23 ] had built the finite element model of the perforated honeycomb-corrugation hybrid to analyze its absorption properties and research viscous-thermal energy dissipation.…”

Section: Introductionmentioning

confidence: 99%

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Development of Adjustable Parallel Helmholtz Acoustic Metamaterial for Broad Low-Frequency Sound Absorption Band

Yang

Shen

et al. 2022

Materials

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For the common difficulties of noise control in a low frequency region, an adjustable parallel Helmholtz acoustic metamaterial (APH-AM) was developed to gain broad sound absorption band by introducing multiple resonant chambers to enlarge the absorption bandwidth and tuning length of rear cavity for each chamber. Based on the coupling analysis of double resonators, the generation mechanism of broad sound absorption by adjusting the structural parameters was analyzed, which provided a foundation for the development of APH-AM with tunable chambers. Different from other optimization designs by theoretical modeling or finite element simulation, the adjustment of sound absorption performance for the proposed APH-AM could be directly conducted in transfer function tube measurement by changing the length of rear cavity for each chamber. According to optimization process of APH-AM, The target for all sound absorption coefficients above 0.9 was achieved in 602–1287 Hz with normal incidence and that for all sound absorption coefficients above 0.85 was obtained in 618–1482 Hz. The distributions of sound pressure for peak absorption frequency points were obtained in the finite element simulation, which could exhibit its sound absorption mechanism. Meanwhile, the sound absorption performance of the APH-AM with larger length of the aperture and that with smaller diameter of the aperture were discussed by finite element simulation, which could further show the potential of APH-AM in the low-frequency sound absorption. The proposed APH-AM could improve efficiency and accuracy in adjusting sound absorption performance purposefully, which would promote its practical application in low-frequency noise control.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Development of Adjustable Parallel Helmholtz Acoustic Metamaterial for Broad Low-Frequency Sound Absorption Band

Yang

Shen

et al. 2022

Materials

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“…Even though this effort had helped so far to achieve remarkable improvements, nowadays, an asymptotic limit is being reached in terms of efficiency. 9 For this reason, new interests have evolved in studying innovative airframe configurations, low-noise technologies based on metamaterials 10,11 and the use of advanced propulsive systems. During the last decades, ideas about the noise shielding obtained by installing the engines on top of the fuselage have been conceived for both conventional and innovative aircraft configurations.…”

Section: Introductionmentioning

confidence: 99%

Adaptive RBF with hyperparameter optimisation for aeroacoustic applications

Burghignoli

Rossetti

Centracchio

et al. 2022

International Journal of Aeroacoustics

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The present work reports an investigation on the use of adaptive metamodels based on radial basis functions (RBFs) for aeroacoustic applications of highly innovative configurations. The relevance of the topic lies on the paramount importance of metamodelling techniques within the design optimisation process of disruptive aircraft layouts. Indeed, the air traffic growth, consequently the hard environmental constraints imposed by regulations, will make a technological breakthrough, an imperative need within few years. As a consequence, the engineering community is paying particular attention to the development of innovative techniques for the design of unconventional configurations. For this class of applications, the designer cannot successfully rely on historical data or low-fidelity models, and the expensive direct simulations remain the only valuable design strategy. In this regard, it can be demonstrated that the use of surrogate models, i.e., metamodels, significantly reduces the computing costs, especially in view of a robust approach to the optimised design. In order to further improve the efficiency of metamodel-based techniques, dynamic approaches based on hyperparameter optimisation and adaptive sampling procedures have been recently developed. The case study presented here pertains the exploiting of dynamic RBF-based metamodels for noise shielding applications. The analysis of the metamodel performances and its convergence properties shows how the final number of direct simulations is significantly reduced by the hyperparameter optimisation algorithm, still strongly depending on the choice of the RBF kernel function.

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“…The potential of metamaterials in aeroacoustics has been recently indicated [8,9] and shown in several works [10][11][12][13][14][15][16]. The particular metamaterials class of the phase-gradient metasurfaces (PGMSs), devoted to sound redistribution more than absorption, has been used to significantly change the noise emission directivity of simple 2D rectangular ducts in numerical simulations [17,18], and, while some technological challenges still remain open, possible synergies with standard liners were speculated. An analytic equivalence between a PGMS and a metafluid designed within the Transformation Acoustics framework was developed in [18,19].…”

Section: Introductionmentioning

confidence: 99%

“…The particular metamaterials class of the phase-gradient metasurfaces (PGMSs), devoted to sound redistribution more than absorption, has been used to significantly change the noise emission directivity of simple 2D rectangular ducts in numerical simulations [17,18], and, while some technological challenges still remain open, possible synergies with standard liners were speculated. An analytic equivalence between a PGMS and a metafluid designed within the Transformation Acoustics framework was developed in [18,19]. The metafluid model demonstrated to be a computationally efficient method to address the simulation-based optimisation of the metasurface parameters, enlightening also new paths for building PGMS devices still unexplored.…”

Section: Introductionmentioning

confidence: 99%

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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On the integration of acoustic phase-gradient metasurfaces in aeronautics

Cited by 12 publications

References 21 publications

Development of Adjustable Parallel Helmholtz Acoustic Metamaterial for Broad Low-Frequency Sound Absorption Band

Development of Adjustable Parallel Helmholtz Acoustic Metamaterial for Broad Low-Frequency Sound Absorption Band

Adaptive RBF with hyperparameter optimisation for aeroacoustic applications

Innovative Acoustic Treatments of Nacelle Intakes Based on Optimised Metamaterials

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