Non-linear interaction of multiple tones on perforated liners

Serrano, Pablo G.; Gabard, Gwénaël; Murray, Paul; Astley, R.J.

doi:10.2514/6.2016-2790

Cited by 2 publications

(4 citation statements)

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“…where ju n j is the surface acoustic particle velocity component normal to the perforated plate, 1 À r 2 is an experimentally derived dimensionless entrance and exit loss coefficient of flow at the perforate orifice, and C D is the hole discharge coefficient. Apart from the non-linear resistance response, clear evidence of non-linearity in the face sheet reactance with respect to the sound pressure level (SPL) was observed by Hersh et al, 4 Murray and Astley 6 and Serrano et al 7 With increasing SPL, the face sheet reactance component reduces as the amplitude of the particle displacement through the perforate holes becomes greater than the hole diameter. The normalised non-linear perforate acoustic reactance is given by…”

Section: Liner Impedance Model -Interior Boundary Conditionmentioning

confidence: 99%

“…Empirical and semi-empirical models predicting the installed impedance of acoustic liners are documented in the scientific literature. 3,[6][7][8] However, there have been relatively few attempts to investigate the dedicated design of liner resistive sheets and cavity geometries for sound absorption over a broad range of frequencies. Jones and Parrot 9 developed a group of parallel-element, narrow-chamber liners constructed from ceramic tubular material with an effective percentage of open area (POA eff ) of 57%.…”

Section: Introductionmentioning

confidence: 99%

“…Also today, additive manufacturing processes make complex acoustic liner designs feasible. 7,[13][14][15] The aim of this initial work is to develop novel acoustic liner concepts with improved normal incidence broadband absorption using a finite element (FE) impedance tube test model developed using the COMSOL Multiphysics modeling software. Particular interest will be on the design of the liner cavity with complex internal structures.…”

Section: Introductionmentioning

confidence: 99%

“…International Journal of Aeroacoustics 20 (5)(6)(7) low and high frequency solutions (minimum distance between tangent of Pareto front and the axis origin).…”

mentioning

confidence: 99%

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Slanted septum and multiple folded cavity liners for broadband sound absorption

Palani

Murray

McAlpine

et al. 2021

International Journal of Aeroacoustics

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The design of acoustic liners with complex cavities for a wide frequency range of attenuation using numerical method is investigated in this paper. Three novel liner concepts are presented, demonstrating predicted improvements in broadband sound absorption when compared with that for conventional designs. The liners include a slanted septum core, a slanted septum core with varying percentage open area, and a MultiFOCAL concept. A finite element model of a normal incidence impedance tube is developed using COMSOL Multiphysics modeling software to predict the acoustic properties (resistance and reactance) of liners at medium and high sound pressure levels, and to study the impact of variations in the liner design parameters. The impedance tube finite element model incorporates non-linear semi-empirical impedance equations, validated by comparing numerical results with measurements performed on a single-degree-of-freedom liner, with a perforated face sheet, at high sound pressure level. The design variables of the novel liner concepts are optimized using a hybrid automated optimisation procedure. The low-frequency optimum slanted septum core concept with an open area of 4.5% for the face sheet and 18% for the short slanted septum is predicted to have an absorption level of at least 14 dB in the frequency range of 400–1000 Hz for normally incident pure tone excitations at 150 dB. The slanted septum core concept with varying percentage open area, with broadband optimum design variables, is predicted to have good broadband sound absorption levels of at least 10 dB in the frequency range of 570–3800 Hz. Finally, the MultiFOCAL liner concept with optimised percentage open areas is predicted to have an excellent broadband sound absorption levels of at least 14 dB, for pure tone excitations at 150 dB, in the frequency range of 900–5300 Hz. This work will be followed by optimisation of the face sheet geometries of these novel liner designs in order to maximise lined duct attenuation for aircraft engine applications.

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Section: Liner Impedance Model -Interior Boundary Conditionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…International Journal of Aeroacoustics 20 (5)(6)(7) low and high frequency solutions (minimum distance between tangent of Pareto front and the axis origin).…”

mentioning

confidence: 99%

See 2 more Smart Citations