Bay cavity noise for full-scale nose landing gear: A comparison between experimental and numerical results

Neri, Eleonora; Kennedy, John; Bennett, Gareth J.

doi:10.1016/j.ast.2017.11.016

Cited by 38 publications

(25 citation statements)

References 14 publications

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“…In fact, with respect to aeronautics, typically only the first or second height mode resonance is considered when designing to avoid aeroacoustic cavity noise, such as from burst-disk cavities or vent holes. However, for much larger volumes, such as landing-gear wheel bays or missile bays, higher-order modes have been shown to be excitable within the velocity range of aircraft on approach to landing [49][50][51][52], and as such, deserve to be examined in the literature.…”

Section: A Numerical Analysis: Wave Expansion Methodsmentioning

confidence: 99%

Cavity Resonance Suppression Using Fluidic Spoilers

Bennett¹,

Okolo²,

Zhao³

et al. 2019

AIAA Journal

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This paper examines experimentally the use of a fluidic spoiler to suppress the resonance within a partially closed cylindrical cavity subject to a grazing flow. The relative movement of aircraft and high-speed land-based vehicles through air often results in structural cavities in these vehicles being subject to shear-layer-driven resonance. This can lead to high-amplitude pressure fluctuations within the cavity volume, causing damage to stores or equipment found within landing-gear wheel or weapon bays, for example, or else significant discomfort to the passengers of cars or trains. This large-scale buffeting can also cause vehicle stability problems and can increase drag. This work presents a novel method, in which passive flow control consisting of an upstream fluidic spoiler is used to redirect the upstream flow so that the cavity orifice is shielded. As a result, the grazing flow can no longer detach from the upstream leading edge of the cavity, and thus, vortex shedding is suppressed. The scope of the study includes an examination of higherorder azimuthal acoustic modes excited in the cylindrical cavity: modes which have received little attention in the literature, but which can be readily excited for many flow configurations for partially covered cavities.

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Section: A Numerical Analysis: Wave Expansion Methodsmentioning

confidence: 99%

Cavity Resonance Suppression Using Fluidic Spoilers

Bennett¹,

Okolo²,

Zhao³

et al. 2019

AIAA Journal

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“…An additional comment from this work is that, although in the paper by Neri et al [28] it was concluded that the addition of the landing gear into the bay along with attaching the doors resulted in the suppression of the tonal noise, it seems, in fact, that it is the doors, in particular, that cause full suppression. The addition of the main strut and drag stay is sufficient to partially attenuate the Helmholtz resonance, but it requires the addition of the doors also to fully attenuate it and the first duct tone.…”

Section: Effect Of Main Strut and Drag Stay On Wheel Well Noisementioning

confidence: 75%

“…Differences in loading in the tunnel seem to have had an effect on the BPF frequencies so that, when the spectrograms are calculated through subtraction, due to the slight frequency shift, the two peaks do not cancel out but instead result in a high positive peak and negative dip remaining. The reader is directed to Neri et al [28] for further discussion. There is, however, an additional lower amplitude reduction at 200 Hz, which covers a wide range of angles.…”

Section: Effect Of the Wheels: Nlg-dresswmentioning

confidence: 99%

“…These 32 and 104 Hz tones are caused by the Helmholtz resonance and the first resonant duct mode of the empty wheel bay. An extensive analysis of these tones and the noise-generating behavior of the wheel well was performed already for the ALLEGRA data by Neri et al [28], and so only a few summary comments will be provided here along with an additional observation. The previous study found that Helmholtz resonance and high-amplitude cavity resonance of the first two duct modes of the wheel well can be measured by the farfield microphones for the NB configuration (i.e., when the bay is empty of the gear and the doors are removed).…”

Section: Effect Of Main Strut and Drag Stay On Wheel Well Noisementioning

confidence: 99%

“…However, it is this very behavior of how components can suppress or amplify the noise generation of the components they neighbor that this study examines. The open bay, as another example, has been demonstrated to radiate significant tonal noise at its Helmholtz frequency and first two standing wave duct resonance tones in the velocity range of a landing aircraft [28], with equivalent tones found for the main landing gear (MLG) test setup, even with the leg in situ [29]. Such tones or high internal pressure amplitudes would be problematic for weapons bays or for passengers in vehicles with open windows, but we see in this study that the presence of the doors and main leg is sufficient to disrupt the shear layer so that these tones are no longer excited.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Noise Characterization of a Full-Scale Nose Landing Gear

Bennett

Neri

Kennedy

2018

Journal of Aircraft

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This paper presents experimental results from a nose landing-gear test campaign. A highly detailed model of the nose section of a 90-seat configuration green regional aircraft concept was built and tested in an aeroacoustic open-jet wind tunnel at full scale. All of the landing-gear components, fixtures, and small details and associated structures such as the complete wheel bay, bay doors, and hydraulic dressings were included at full scale. This paper focuses on one element of the testing: that of component noise assessment. The dressings, wheels, torque link, steering pinion, bay doors, and then the main strut and drag stay were removed in succession, and an acoustic evaluation was performed at a range of velocities from M 0.12 to M 0.19. In addition, hub caps were installed on the wheels, and their performance as a low-noise treatment is presented and assessed for efficacy. The landing gear, doors, and bay generated most noise in the frequency range between 120 and 400 Hz, but appreciable noise above the baseline was measured up to 10 kHz. The low-to midfrequency aerodynamic noise was found to scale with V 6 , as usual; however, the spectra at high frequencies collapsed perfectly when scaled to V 7 , confirming the fact that high-frequency noise is radiated from the turbulent flow surrounding small features. The total noise output of the landing-gear assembly differs from that of the sum of the components in isolation due to installation effects. The research in this paper studied these effects and the influence of the components on each other.

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Air Curtain Flow Control for Aerodynamic Noise Reduction

Bennett

Zhao

2020

Notes on Numerical Fluid Mechanics and Multidisciplinary Design

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Bay cavity noise for full-scale nose landing gear: A comparison between experimental and numerical results

Cited by 38 publications

References 14 publications

Cavity Resonance Suppression Using Fluidic Spoilers

Cavity Resonance Suppression Using Fluidic Spoilers

Noise Characterization of a Full-Scale Nose Landing Gear

Air Curtain Flow Control for Aerodynamic Noise Reduction

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