Computational Aeroacoustics

Manoha, Eric; Redonnet, Stephane; Caro, Stéphane

doi:10.1002/9780470686652.eae344

Cited by 4 publications

(1 citation statement)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such approximations are considered reasonable for an initial estimate of engine noise shielding in the design of a new aircraft concept. The large dimensions of the aircraft and distances between sources and observers together with the complex nature of the engine noise emissions result in computational times of computer fluid dynamics simulations incompatible with an optimization procedure required in the design phase of an aircraft (Manoha et al, 2010).…”

mentioning

confidence: 99%

Analysis of shielding of propeller noise using beamforming and predictions

Vieira

Snellen

Malgoezar

et al. 2019

The Journal of the Acoustical Society of America

View full text Add to dashboard Cite

Engine noise shielding is an important measure towards low-noise aircraft configurations. Such designs are supported by prediction tools that indicate high values for shielding of engine noise. Most prediction models approximate the complex nature of engine noise to simple noise sources such as monopoles or dipoles. This work compares predictions of noise shielding with experiments using different noise sources and shielding body geometries. The experiments considered in this work concern a monopole source shielded by a flat plate and a NACA 64-008 A wing, and a propeller shielded by the same wing. Comparisons between models and measurements are made by analysis of noise levels at individual microphones and using conventional beamforming. Results show that for the monopole cases the model predictions are in agreement with the experimental data, with an average deviation of 2–3 dB. The curvature of the leading edge of the wing influences the noise shielding results. The measured values of noise shielding of propeller noise are lower than those measured for the omni-directional source. Different types of source directivity are used to approximate the propeller in the predictions: monopole, dipole and a multi-source. The dipole approximation shows the best agreement with the experiments for the case of the propeller.

show abstract

mentioning

confidence: 99%

Analysis of shielding of propeller noise using beamforming and predictions

Vieira

Snellen

Malgoezar

et al. 2019

The Journal of the Acoustical Society of America

View full text Add to dashboard Cite

show abstract

Further assessment of a time domain impedance boundary condition for the numerical simulation of noise-absorbing materials

Redonnet

2021

International Journal of Aeroacoustics

View full text Add to dashboard Cite

In regard to the mitigation of environmental noise across major industry sectors, the present study focuses on the numerical prediction of passive noise reduction devices. Here, it is further explored how the noise attenuation induced by locally reacting noise absorbing materials (also called acoustic liners) can be simulated using a time domain highly accurate Computational AeroAcoustics (CAA) method. To this end, it is assessed how a classical Time Domain Impedance Boundary Condition (TDIBC) can effectively model acoustic liners of practical interest, including when the latter are exposed to realistic conditions (grazing flow and noise excitation). The investigation consists in numerically reproducing two experimental campaigns initially performed at NASA Langley Research Center. Two different materials are considered (honeycomb superimposed with perforate or wiremesh resistive face-sheet), each being characterized by a specific noise attenuation behaviour ( e.g. dependency on the flow conditions and/or noise excitation). Each material is tested under various flow conditions ( e.g. grazing flow of Mach up to 0.5) and/or noise source excitation ( e.g. multiple tones of level up to 140 dB each). The results demonstrate the ability of the underlying CAA/TDIBC approach to simulate realistic acoustic liners in non-trivial configurations, with enough physical accuracy ( e.g. correct capture of the noise attenuation characteristics) and numerical robustness ( e.g. absence of instabilities). The study also reveals that, independent from the CAA/TDIBC approach itself, some specific pre-processing tasks (e.g. impedance eduction and subsequent TDIBC calibration) may play a bigger role than expected, in practice.

show abstract