Numerical Simulations of Fan Interaction Noise Using a Hybrid Approach

Polacsek, Cyril; Burguburu, S.; Redonnet, Stephane; Terracol, Marc

doi:10.2514/1.10688

Cited by 44 publications

(13 citation statements)

References 18 publications

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“…In this context, at ONERA [51][52][53][54][55][56][57], a high-order overlapping grid method for coupling Cartesian and curvilinear grids is developed in order to simulate aerodynamic noise. The overlapping grid method is based on Lagrange interpolating polynomials and a theoretical analysis of the interpolation operator is then carried out.…”

Section: The High-order Finite Differences Methodsmentioning

confidence: 99%

High accuracy flow simulations: Advances and challenges for future needs in aeronautics

2011

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Section: The High-order Finite Differences Methodsmentioning

confidence: 99%

High accuracy flow simulations: Advances and challenges for future needs in aeronautics

2011

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“…The focus is now put on the far-field acoustic power, which can differ from the in-duct acoustic power if the dominant modes have a low radiation efficiency or if some cut-off modes reach the inlet plane with a significant level [24]. The Kirchhoff's integral method is applied in the frequency-domain to get the far-field pressure at BPFn from the pressure field on a source surface S at the same frequency [25,26]. One should note that solving the equation of Ffowcs Williams…”

Section: B Far-field Acoustic Powermentioning

confidence: 99%

“…and Hawkings [27] is not needed when focusing on the sound radiation by the intake. For an observer point x = (x, y, z), the pressure at BPFn p n (x) therefore writes [25]:…”

Section: B Far-field Acoustic Powermentioning

confidence: 99%

Shock Wave Generation and Radiation from a Turbofan Engine Under Flow Distortion

2020

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This paper presents aeroacoustic investigations on a full-scale Ultra High Bypass Ratio (UHBR) engine with inflow distortion at transonic conditions. Computational Fluid Dynamics (CFD) simulations are first realized to compute the shocks in the vicinity of the fan. These shocks are then radiated in the near-field thanks to Computational AeroAcoustics (CAA) simulations. The chaining between CFD and CAA simulations is done by injecting the shocks in terms of usual conservative variables using a non-reflecting boundary condition. The CAA solver is based on the non-linearized Euler equations which allows to define the CFD/CAA interface close to the fan where the propagation of shocks is highly non-linear. Both shock generation and propagation mechanisms are investigated and the effects of inflow distortion are highlighted by comparison with a baseline case without distortion. The flow distortion is shown to be responsible for a modification of shock amplitudes along the circumferential direction. Thus, azimuthal modes appear in addition to the rotor-locked mode present without distortion. A particular feature of the studied configuration is the presence of a supersonic flow region in the bottom part of the nacelle. This supersonic pocket blocks the shocks in the lower half of the nacelle and also modifies the angle at which they leave the nacelle in its upper half. Consequently, the far-field radiation (obtained using Kirchhoff's integral method) is mainly oriented skywards and towards the side of descending blades. Acoustic power estimates are provided to quantify these effects. Nomenclature a = speed of sound of the uniform far-field flow, m/s a 0 = time-averaged speed of sound, m/s B = number of rotor blades CDC = circumferential distortion coefficient

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“…The surfaces were extracted from the CFD multi-block structured grid used for the CFD. A first set of rigid surfaces includes the wall surfaces on the wing leading edge (1-7) and on the slat pressure side (8)(9)(10)(11). Then, three sets of porous surfaces are available near the external boundary of the computational domain.…”

Section: American Institute Of Aeronautics and Astronauticsmentioning

confidence: 99%

Slat noise measurement and numerical prediction in the VALIANT programme

Manoha¹,

Terracol²,

Lemoine

et al. 2012

18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference)

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In the context of the on-going EC research program VALIANT, mechanisms of slat noise generation are studied on the basis of a simple but representative 2-element (slat and main body) airfoil, for which a detailed experimental aerodynamic/acoustic database has been collected in the open jet facility at Ecole Centrale de Lyon (ECL) at a Reynolds number, based on the airfoil chord, of about one million. Then several CFD/CAA prediction methods have been compared, improved and validated against this database.The airfoil shape has been optimized by Onera with the objectives of isolating the slat noise sources from other spurious sources, while minimizing the airfoil total lift and the wind tunnel mean flow deflection. The tests at ECL provided aerodynamic data (static and unsteady wall pressure data, hot-wire probe measurements) and farfield noise acquisitions, including directivity characterization and noise sources localization using Onera's microphone antenna. Then an unsteady zonal hybrid RANS/LES simulation has been performed using Onera's FUNk solver, providing a comprehensive description and physical analysis of the unsteady flow inside the slat cove. The computed and measured wall pressure spectra are in fair qualitative and quantitative agreement, both being characterized by several tonal peaks emerging from a global broadband content. The noise maps confirmed that these peaks are actually generated by the slat cove region. These tones are attributed to a cavity feedback loop mechanism involving the impact of the main shear layer on the slat pressure side, and a theoretical law predicting the tone frequencies has been proposed. Finally, a farfield noise prediction is achieved, using a Ffowcs Williams-Hawking integration (Onera's MIA solver), from CFD unsteady data stored on a porous surface located at the external boundaries of the CFD domain. Corrections are proposed to account for (i) the difference between experimental and computational airfoil spans, based on un-correlated spanwise duplication of the CFD domain, (ii) the acoustic installation effects, studied via BEM computations using Onera's Bemuse solver, due to the test set-up side plates and the airfoil surfaces which were not included in the CFD domain. With these corrections, measured and predicted farfield noise spectra and overall sound pressure levels are in fair agreement. I ContextIn the on-going EC research program VALIANT (VALidation and Improvement of Airframe Noise prediction Tools) coordinated by the Von Karman Institute (Brussels, Belgium) basic mechanisms of airframe noise (AFN) are studied through a dual approach, • to generate a detailed, accurate experimental database on broadband noise associated with simple but representative configurations, including the turbulent flow sources causing the noise and, • to validate and improve CFD/CAA tools for prediction of the corresponding type of broadband AFN and generate a detailed numerical database. The following specific flow configurations revealing the basic mechanisms of AFN generated by ...

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Numerical Simulations of Fan Interaction Noise Using a Hybrid Approach

Cited by 44 publications

References 18 publications

High accuracy flow simulations: Advances and challenges for future needs in aeronautics

High accuracy flow simulations: Advances and challenges for future needs in aeronautics

Shock Wave Generation and Radiation from a Turbofan Engine Under Flow Distortion

Slat noise measurement and numerical prediction in the VALIANT programme

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