Noise reduction potential of flow permeable materials for jet-flap interaction noise

Schmidt, Johannes Dragsbæk; Jente, Christian; Rossignol, Karl-Stéphane; Siller, H.

doi:10.2514/6.2022-3040

Cited by 6 publications

(3 citation statements)

References 8 publications

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“…Recent efforts have been directed at the modification of the flap instead. Porous media inserted in the flap trailing edge can yield up to 10 dB noise reduction when the flap is located in the hydrodynamic region of the jet [23][24][25][26]. Acoustic liners on the flap [27] showed also noise reductions in the order of 7 dB and 10 dB on the far-field spectra, at the resonant frequency of single and double degree-of-freedom liners, respectively.…”

Section: Introductionmentioning

confidence: 99%

Jet noise and wing installation effects of circular, beveled and rectangular nozzles

Christophe

Decker

Schram

2023

Preprint

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With the growth of modern turbofan engines, their integration under the wing becomes challenging and induces aerodynamic and acoustic interactions between the jet exhaust and the airframe. Jet noise reduction techniques have been widely studied over the past decades but their efficiency has still to be demonstrated once installed. The present lab-scale jet experiments at Mach 0.6 compare the noise radiated by beveled and rectangular installed nozzles to circular ones on a quarter-sphere radiation map using a microphone antenna. For all radiation angles, modified nozzles show an amplitude decrease of the jet-plate interaction tones of the noise spectra attributed to a strong coupling between the jet shear layers and the sound scattering at the plate trailing edge. Circular nozzles achieve a noise reduction for all radiation angles with a maximum decrease up to 2~dB at receiver locations perpendicular to the plate. While rectangular nozzles show a similar behavior, a sound increase is observed for listeners parallel to the plate when the height-to-width ratio is small.

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Section: Introductionmentioning

confidence: 99%

Jet noise and wing installation effects of circular, beveled and rectangular nozzles

Christophe

Decker

Schram

2023

Preprint

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“…There exist a number of studies which investigate passive control strategies for installation noise. Rego et al (2021) and later Jente et al (2022) investigated the potential of using permeable surfaces to reduce installation noise. In a similar approach, Kamliya Jawahar et al (2023) studied porous plates to achieve installation noise reduction.…”

Section: Introductionmentioning

confidence: 99%

Modeling closed-loop control of installation noise using Ginzburg-Landau equation

Karban¹,

Martini²,

Jordan³

2023

Preprint

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Installation noise is a dominant source associated with aircraft jet engines. Recent studies show that linear wavepacket models can be employed for prediction of installation noise, which suggests that linear control strategies can also be adopted for mitigation of it. We present here a simple model to test different control approaches and highlight the potential restrictions on a successful noise control in an actual jet. The model contains all the essential elements for a realistic representation of the actual control problem: a stochastic wavepacket is obtained via a linear Ginzburg-Landau model; the effect of the wing trailing edge is accounted for by introducing a semi-infinite half plane near the wavepacket; and the actuation is achieved by placing a dipolar point source at the trailing edge, which models a piezoelectric actuator. An optimal causal resolvent-based control method is compared against the classical wave-cancellation method. The effect of the causality constraint on the control performance is tested by placing the sensor at different positions. We demonstrate that when the sensor is not positioned sufficiently upstream of the trailing edge, which can be the case for the actual control problem due to geometric restrictions, causality reduces the control performance. We also show that this limitation can be moderated using the optimal causal control together with modelling of the forcing.

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“…To address the additional noise produced by installed jets, and thereby enable the use of efficient ultra high bypass ratio turbofan engines, several noise reduction technologies (NRTs) have been developed. These include, but are not limited to, porous trailing edges [7,8], swept trailing edges [9], active flow control [10], and chevron nozzles [11]. Of these, the chevron nozzle is perhaps the most mature, given that it is currently in active service on a number of commercial aircraft.…”

Section: Introductionmentioning

confidence: 99%

Aeroacoustic Analysis of a Closely Installed Chevron Nozzle Jet using the High-Order Discontinuous Galerkin Method

Lindblad

Sherwin

Cantwell

et al. 2023

AIAA AVIATION 2023 Forum

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In this paper, we use Large Eddy Simulations (LES) in combination with the Ffowcs Williams -Hawkings method to study the influence of chevrons on the flow field as well as the noise produced by a closely installed M = 0.6 jet. The LES simulations are performed with the spectral/hp element framework Nektar++ (www.nektar.info). Nektar++ uses the high-order discontinuous Galerkin method and an implicit scheme based on the matrix-free Newton-GMRES method to discretize the unfiltered Navier-Stokes equations in space and time, respectively. The far-field noise is computed using Antares (www.cerfacs.fr/antares/). Antares solves the Ffowcs Williams -Hawkings equation for a permeable integration surface in the time-domain using a source-time dominant algorithm. The aerodynamic results show good agreement with experimental data obtained in the Doak Laboratory Flight Jet Rig, located at the University of Southampton. Some discrepancies are observed in terms of the far-field noise levels, especially for higher polar observer angles relative to the downstream jet axis. In terms of noise reduction potential, the simulations predict that the chevrons reduce the OASPL by 1dB compared to an installed round nozzle for all observers located on the unshielded side of the wing. This should be compared to the experiments, which predict a 1.5dB noise reduction for the same chevron nozzle.

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Noise reduction potential of flow permeable materials for jet-flap interaction noise

Cited by 6 publications

References 8 publications

Jet noise and wing installation effects of circular, beveled and rectangular nozzles

Jet noise and wing installation effects of circular, beveled and rectangular nozzles

Modeling closed-loop control of installation noise using Ginzburg-Landau equation

Aeroacoustic Analysis of a Closely Installed Chevron Nozzle Jet using the High-Order Discontinuous Galerkin Method

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