Impedance assessment of a dual-resonance acoustic liner

Beck, Benjamin S.; Schiller, Noah H.; Jones, Michael G.

doi:10.1016/j.apacoust.2015.01.011

Cited by 30 publications

(19 citation statements)

References 23 publications

(22 reference statements)

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“…The basic single degree-of-freedom liner is typically made by an hard-backed honeycomb and behaves like a quarter-wavelength resonator, covered by a perforated plate that, on one side, enhances the sound absorption of the liner and on the other, maintains the aerodynamic flow as cleanly as possible on the walls of the nacelle. Liner design is one of the most active research field in aeronautics and recently, metamaterials have started to be taken into consideration for future and more effective absorbing panels for liners, adopting e.g., dual-resonant materials covered by microperforated panels [42,43] or variable depth liners with spherical inclusions and microporous panels embedded within melamine [44].…”

Section: Absorption and Dissipationmentioning

confidence: 99%

“…The corrugated structure exhibited several resonant frequencies that caused the air in the perforation to oscillate severely when excited, thus dissipating energy in the viscous boundary layer, obtaining a broadband high absorption coefficient for a wide range of incident angles of acoustic perturbation. Various metamaterial designs for low-frequency absorption: (a) a membrane decorated with added platelets and displacement related to the first three eigenfrequencies of the structure from [47]; (b) a dual resonant metamaterial composed of Helmholtz's resonators, and a perforated sheet adopted as an innovative liner in [43]; (c,d) two different space-coiling designs, respectively from [45] and [46]. The dissipation of acoustic energy is fundamental in each design.…”

Section: Absorption and Dissipationmentioning

confidence: 99%

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Acoustic Metamaterials in Aeronautics

et al. 2018

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Metamaterials, man-made composites that are scaled smaller than the wavelength, have demonstrated a huge potential for application in acoustics, allowing the production of sub-wavelength acoustic absorbers, acoustic invisibility, perfect acoustic mirrors and acoustic lenses for hyper focusing, and acoustic illusions and enabling new degrees of freedom in the control of the acoustic field. The zero, or even negative, refractive sound index of metamaterials offers possibilities for the control of acoustic patterns and sound at sub-wavelength scales. Despite the tremendous growth in research on acoustic metamaterials during the last decade, the potential of metamaterial-based technologies in aeronautics has still not been fully explored, and its utilization is still in its infancy. Thus, the principal concepts mentioned above could very well provide a means to develop devices that allow the mitigation of the impact of civil aviation noise on the community. This paper gives a review of the most relevant works on acoustic metamaterials, analyzing them for their potential applicability in aeronautics, and, in this process, identifying possible implementation areas and interesting metabehaviors. It also identifies some technical challenges and possible future directions for research with the goal of unveiling the potential of metamaterials technology in aeronautics.

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Section: Absorption and Dissipationmentioning

confidence: 99%

Section: Absorption and Dissipationmentioning

confidence: 99%

Acoustic Metamaterials in Aeronautics

et al. 2018

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“…Liner design is one of the most active research field in aeronautics and recently metamaterials are starting to be taken into consideration for future and more effective absorbing panels for liners, adopting e.g. dual-resonant materials covered by microperforated panels [41,42] or variable depth liners with spherical inclusions and microporous panels embedded within melamine [43]. The most desired effect that could be possibly achieved by adopting metamaterial inspired liners is low frequency absorption, i.e.…”

Section: Absorption and Dissipationmentioning

confidence: 99%

Acoustic Metamaterials in Aeronautics

Palma¹,

Mao²,

Burghignoli³

et al. 2018

Preprint

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Metamaterials, man-made composites scaled smaller than the wavelength, have demonstrated a huge potential in their applications in acoustics, opening up for sub--wavelength acoustic absorbers, acoustic invisibility, perfect acoustic mirrors and acoustic lenses for hyper focusing, acoustic illusions and enabling new degrees of freedom in the control of the acoustic field. The zero, or even negative, refractive sound index of metamaterials offers possibilities in control of the acoustic pattern and sound at sub--wavelength scales. Despite the tremendous growth of the research on acoustic metamaterials during the last decade, the potential of metamaterial-based technologies in aeronautics is still not fully explored and its utilization is still in its infancy. Thus the principal concepts mentioned above could very well provide means to develop devices that would allow the mitigation of the impact of the civil aviation noise on the community. This paper gives a review of the state of the art of the most relevant works on acoustic metamaterials, analyzing them against their potential applicability in aeronautics, and in this process identifying possible implementation areas and interesting metabehaviors. It also identifies some technical challenges and possible future directions for research with the goal of unveiling the potential of metamaterials technologies in aeronautics.

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“…[3][4][5][6][7] To overcome these limitations to make use of metamaterials in engineering applications, we can first refer to prior studies on this topic. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] The concepts of metamaterials were utilized to overcome the diffraction limits of ultrasonic and acoustic devices or superlenses. [8][9][10]21 A superlens is a lens that utilizes metamaterials that function beyond the diffraction limit.…”

Section: Introductionmentioning

confidence: 99%

An Acoustic Hyperlens with Negative Direction Based on Double Split Hollow Sphere

Choi

Yoon

2019

J. Theor. Comp. Acout.

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This study develops a new acoustic negative-refraction metamaterial that utilizes a synthesized double split hollow sphere (DSHS) for its unit cell. Recent relevant research has affirmed the concept that acoustic metamaterials can show unusual behavior that has not been observed in nature previously. However, as some hypothetical metamaterial designs have material properties not found in nature, the realization of practical metamaterials requires practical and complicated models. As a contribution to the development of acoustic metamaterials, the present study proposes a new anisotropic unit structure that encompasses Helmholtz resonators. This structure is referred to as the DSHS, is easy to manufacture, and has the advantage in that it uses the natural medium in its original form. By drawing the equifrequency or isofrequency contours of the designed two-dimensional (2D) anisotropic unit structure using the Floquet–Bloch’s principle, the properties of the present metamaterial can be understood. Numerical simulations are also conducted to identify and present the characteristics of the presented acoustic metamaterial. Through these, a new refraction phenomenon is identified that deviates from Snell’s law, and an acoustic hyperlens is numerically implemented that overcomes the diffraction limit.

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Impedance assessment of a dual-resonance acoustic liner

Cited by 30 publications

References 23 publications

Acoustic Metamaterials in Aeronautics

Acoustic Metamaterials in Aeronautics

Acoustic Metamaterials in Aeronautics

An Acoustic Hyperlens with Negative Direction Based on Double Split Hollow Sphere

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