A Comparison of Ffowcs Williams-Hawkings Solvers for Airframe Noise Applications

Lockard, David P.

doi:10.2514/6.2002-2580

Cited by 91 publications

(60 citation statements)

References 14 publications

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“…Significant velocity fl uctuations are also present around the sidebars. Although the FW-H equation has been used successfully for cylinder shedding problems 9,25 when wakes encounter porous surfaces, errors are generated as the vortices pass through because the volumetric contribution, which is neglected, should cancel some of the surface terms that are included. When the strength of the vortices is sufficiently large, errors can be generated that are of the same order of the radiated noise.…”

Section: Porous Surface Predictionsmentioning

confidence: 99%

Aeroacoustic Analysis of a Simplified Landing Gear

Lockard

Khorrami

2003

9th AIAA/CEAS Aeroacoustics Conference and Exhibit

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A hybrid approach is used to investigate the noise generated by a simplified landing gear without small scale parts such as hydraulic lines and fasteners. The Ffowcs Williams and Hawkings equation is used to predict the noise at far-field observer locations from flow data provided by an unsteady computational fluid dynamics calculation. A simulation with 13 million grid points has been completed, and comparisons are made between calculations with different turbulence models. Results indicate that the turbulence model has a profound effect on the levels and character of the unsteadiness. Flow data on solid surfaces and a set of permeable surfaces surrounding the gear have been collected. Noise predictions using the porous surfaces appear to be contaminated by errors caused by large wake fluctuations passing through the surfaces. However, comparisons between predictions using the solid surfaces with the near-field CFD solution are in good agreement giving confidence in the far-field results.

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Section: Porous Surface Predictionsmentioning

confidence: 99%

Aeroacoustic Analysis of a Simplified Landing Gear

Lockard

Khorrami

2003

9th AIAA/CEAS Aeroacoustics Conference and Exhibit

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“…Kirchhoff formulations for stationary and moving surfaces, especially as embodied in the Ffowcs Williams-Hawkings equation [28][29][30], are commonly solved in the frequency domain. Convective effects of uniform flow [31,32] and modification owing to potential flow at low speed [33] can be accounted for in noise predictions. Treatment for two-dimensional flow [34], fast evaluation of the aeroacoustic integrals [35] and the treatment to reduce spurious attribution of vortical outflow as a noise source [36,37] [25] matching that of experiment [26].…”

Section: (A) Computational Algorithmsmentioning

confidence: 99%

A second golden age of aeroacoustics?

Lele

Nichols

2014

Phil. Trans. R. Soc. A.

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In 1992, Sir James Lighthill foresaw the dawn of a second golden age in aeroacoustics enabled by computer simulations (Hardin JC, Hussaini MY (eds) 1993 Computational aeroacoustics, New York, NY: Springer (doi:10.1007). This review traces the progress in large-scale computations to resolve the noise-source processes and the methods devised to predict the far-field radiated sound using this information. Keeping focus on aviation-related noise sources a brief account of the progress in simulations of jet noise, fan noise and airframe noise is given highlighting the key technical issues and challenges. The complex geometry of nozzle elements and airframe components as well as the high Reynolds number of target applications require careful assessment of the discretization algorithms on unstructured grids and modelling compromises. High-fidelity simulations with 200-500 million points are not uncommon today and are used to improve scientific understanding of the noise generation process in specific situations. We attempt to discern where the future might take us, especially if exascale computing becomes a reality in 10 years. A pressing question in this context concerns the role of modelling in the coming era. While the sheer scale of the data generated by large-scale simulations will require new methods for data analysis and data visualization, it is our view that suitable theoretical formulations and reduced models will be even more important in future.

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“…The pressure and velocity on a FW-H surface completely define all noise sources contained inside to any observer outside the surface. The FW-H technique has been successfully used to predict noise by coupling Computational Fluid Dynamics (CFD) and a FW-H solver [30][31][32][33] to provide the noise at the observer. As long as nonlinear effects, such as shocks that cause High Speed Impulsive (HSI) noise in helicopters, 34 and volume sources, such as turbulence in jet exhausts, 35 are inside the surface, their contribution to the far-field noise is defined by the conditions on the surface.…”

Section: Anopp2 Prediction Approachmentioning

confidence: 99%

Design of the Next Generation Aircraft Noise Prediction Program: ANOPP2

Lopes

Burley

2011

17th AIAA/CEAS Aeroacoustics Conference (32nd AIAA Aeroacoustics Conference)

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The requirements, constraints, and design of NASA's next generation Aircraft NOise Prediction Program (ANOPP2) are introduced. Similar to its predecessor (ANOPP), ANOPP2 provides the U.S. Government with an independent aircraft system noise prediction capability that can be used as a stand-alone program or within larger trade studies that include performance, emissions, and fuel burn. The ANOPP2 framework is designed to facilitate the combination of acoustic approaches of varying fidelity for the analysis of noise from conventional and unconventional aircraft. ANOPP2 integrates noise prediction and propagation methods, including those found in ANOPP, into a unified system that is compatible for use within general aircraft analysis software. The design of the system is described in terms of its functionality and capability to perform predictions accounting for distributed sources, installation effects, and propagation through a non-uniform atmosphere including refraction and the influence of terrain. The philosophy of mixed fidelity noise prediction through the use of nested Ffowcs Williams and Hawkings surfaces is presented and specific issues associated with its implementation are identified. Demonstrations for a conventional twin-aisle and an unconventional hybrid wing body aircraft configuration are presented to show the feasibility and capabilities of the system. Isolated model-scale jet noise predictions are also presented using high-fidelity and reduced order models, further demonstrating ANOPP2's ability to provide predictions for model-scale test configurations.

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A Comparison of Ffowcs Williams-Hawkings Solvers for Airframe Noise Applications

Cited by 91 publications

References 14 publications

Aeroacoustic Analysis of a Simplified Landing Gear

Aeroacoustic Analysis of a Simplified Landing Gear

A second golden age of aeroacoustics?

Design of the Next Generation Aircraft Noise Prediction Program: ANOPP2

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