Landing Gear Noise Identification Using Phased Array with Experimental and Computational Data

Bulté, Jean; Redonnet, Stephane

doi:10.2514/1.j055643

Cited by 10 publications

(4 citation statements)

References 43 publications

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“…After some tests, a plane, cross-shaped array of virtual microphones, inspired by that used in Bulté & Redonnet [65] on the LAGOON configuration in the "C19 open-jet" conditions has been retained. It is composed of two orthogonal linear arrays of microphones evenly distributed on a distance of 100D w .…”

Section: Setupmentioning

confidence: 99%

A comparison between off and on-body control surfaces for the FW-H equation: Application to a non-compact landing gear wheel

Hajczak

Sanders

Vincent

et al. 2021

Journal of Sound and Vibration

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This work is a contribution to the ongoing debate about the role of quadrupoles in low Mach number flows, studied through the use of solid and permeable surface Ffowcs-Williams & Hawkings (FW-H) integrals for landing gear numerical noise predictions. It rests upon the key idea that the dominance of surface sources over volume sources can only be guaranteed when the compact-source condition is met. We propose here to express this property as a condition on the smallness of the product between the Mach and Strouhal numbers, or formally as MSt < 1. We consider a canonical isolated wheel, that basically consists in a shallow circular cavity inscribed in a coin-like cylinder, thus presenting few different length scales, as compared to a full landing gear assembly. Zonal Detached Eddy Simulations are performed on several gradually refined grids to assess the grid convergence of the numerical result. In particular, important computational effort is put into the accurate resolution of acoustic waves up to Strouhal numbers such that MSt > 1. Overall, determining the real significance of quadrupoles was challenging as numerical errors or misleading effects such as near-field terms, surface discretization, or source domain truncation biased the initial permeable surface results. Even when these sources of bias are removed, non-negligible differences are found between the solid and permeable noise spectra at non-compact St values, while both formulations are equivalent at lower Strouhal numbers. The analysis of these differences is extended to the determination of their impact on frequency-domain noise maps obtained with the DAMAS algorithm fed with far-field signals computed with both FW-H approaches. A tentative interpretation of the wheel noise sources is finally proposed, highlighting the dominant role of the scattering of aerodynamic sources by the cavity downstream edge at low Strouhal numbers, while wake sources dominate at higher Strouhal numbers.

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Section: Setupmentioning

confidence: 99%

A comparison between off and on-body control surfaces for the FW-H equation: Application to a non-compact landing gear wheel

Hajczak

Sanders

Vincent

et al. 2021

Journal of Sound and Vibration

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“…The phased microphone array is extensively employed in wind tunnels, which offer a controlled environment for the investigation of scaled models [21][22][23] or aircraft components, [24][25][26] although exact replication of flight conditions is difficult due to factors such as modelling accuracy, high background noise level and discrepancy in the Reynolds number.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the free-space acoustic signature of a BBMF Rolls-Royce Merlin engine from 842 rpm to 2740 rpm

Bennett

2021

Proceedings of the Institution of Mechanical Engineers, Part G:

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A technique has been developed to analyse the free-space acoustic signature of the Rolls-Royce Merlin engine in order to provide diagnostic information relating to its performance. The work is motivated by a need to maintain the reliability and maximise the lifetime of this historic engine which is an important component of the aircraft operated by the UK Battle of Britain Memorial Flight (BBMF). For convenience, the data were extracted from the soundtrack of a video recording made whilst the aircraft was undergoing a full-power ground-run. The aim of the work is to generate information relating the individual firings of each cylinder and this is presented as a multi-level colour image. Here, the ignition time history for two revolutions (six ignitions) is shown vertically and corresponds to the bank of exhaust ports facing the microphone. Subsequent similar histories are presented along the horizontal time axis. The results are sensitive to engine speed variations, and a correlation between successive vertical columns is carried out to quantify this drift and adjust the data accordingly. Seven engine speeds from 842 to 2740 rpm are examined. The processed data illustrate that some speeds exhibit well-defined, single ignitions whereas others show varying degrees of after-firing type effects. At the higher engine speeds, it would seem that the cylinder ignition amplitudes become much more irregular, and the results for 2740 rpm indicate a breakdown in engine performance. The coefficient of variation (Cv) has been demonstrated as a measure of these factors. Finally, a technique has been proposed and demonstrated for the identification of individual cylinders in the firing sequence. The data acquisition process is relatively straight-forward and should not demand excessive time to cover a full range of engine speeds. With further investigations, it could be possible to readily relate the imaging results to specific engine faults.

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“…Engine noise and airframe noise are the two main sources of aircraft noise [2]. Turbulence noise contributes considerably to aircraft noise, including engine jet noise [3,4], high-lift device noise [5], and landing gear noise [6].Aeroacoustic prediction is a challenging computational fluid dynamics (CFD) problem because the sound energy is much lower than the flow energy, posing a strong challenge to the numerical method and turbulence model. Two types of computation methods, direct method and hybrid method [7], are commonly used to compute noise.…”

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confidence: 99%

mentioning

confidence: 99%

Aeroacoustic prediction based on large-eddy simulation and the Ffowcs Williams–Hawkings equation

et al. 2022

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A hybrid noise computation method is presented in this paper. Large-eddy simulation with wall-model equation is proposed to compute the flow field. With a stress-balanced wall-model equation, the near-wall computation cost of large eddy simulation was effectively reduced. The instantaneous flow variables obtained by the large-eddy simulation were used to compute the noise source terms of the Ffowcs Williams–Hawkings equation. The present method was investigated with two test cases: a single cylinder at Re = 10,000 and a rod-airfoil at Re = 480,000. The flow quantities and aeroacoustic characteristics were compared with the reference data. The mean velocity profiles and spectra of the flow fluctuations were consistent with data from the literature. When compared with the reference data, the noise computation error was less than 3 dB. The computation results demonstrate the present wall-modeled large eddy simulation is efficient for the noise computation of complex vortex shedding flows.

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Landing Gear Noise Identification Using Phased Array with Experimental and Computational Data

Cited by 10 publications

References 43 publications

A comparison between off and on-body control surfaces for the FW-H equation: Application to a non-compact landing gear wheel

A comparison between off and on-body control surfaces for the FW-H equation: Application to a non-compact landing gear wheel

Analysis of the free-space acoustic signature of a BBMF Rolls-Royce Merlin engine from 842 rpm to 2740 rpm

Aeroacoustic prediction based on large-eddy simulation and the Ffowcs Williams–Hawkings equation

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