Generation and Propagation of Multiple Pure Tones Inside Turbofans at Transonic Regime

Thisse, Johan; Polacsek, Cyril; Léwy, S.; Lafitte, Anthony

doi:10.2514/1.j054007

Cited by 9 publications

(2 citation statements)

References 18 publications

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“…Onera studied the both aspects. Concerning the N-wave propagation, Onera [63] compared the most advanced analytical methods in the time and frequency domains for two representative turbofan configurations (named FANPAC and MASCOT2). The reliability of each method has been discussed through a comprehensive analysis and validated using experimental data.…”

Section: On the Generation And Propagation Of Multiple Pure Tones (Mpmentioning

confidence: 99%

Aeroacoustics research in Europe: The CEAS-ASC report on 2014 highlights

Detandt¹

2015

Journal of Sound and Vibration

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The Council of European Aerospace Societies (CEAS) Aeroacoustics Specialists Committee (ASC) supports and promotes the interests of the scientific and industrial aeroacoustics community on an European scale and European aeronautics activities internationally. Each year the committee highlights some of the research and development projects in Europe. This paper is the 2014 issue of this collection of Aeroacoustic Highlights, compiled from informations submitted to the CEAS-ASC. The contributions are classified in different topics; the first categories being related to specific aeroacoustic challenges (airframe noise, fan and jet noise, helicopter noise, aircraft interior noise) and two last sections are respectively devoted to recent improvements and emerging techniques and to general advances in aeroacoustics. For each section, the present paper focus on accomplished projects, providing the state of the art in each research category in 2014. A number of research programmes involving aeroacoustics were funded by the European Commission. Some of the highlights from these programmes are summarised in this paper, as well as highlights funded by national programmes or by industry.

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Section: On the Generation And Propagation Of Multiple Pure Tones (Mpmentioning

confidence: 99%

Aeroacoustics research in Europe: The CEAS-ASC report on 2014 highlights

Detandt¹

2015

Journal of Sound and Vibration

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“…Many extensions of the FDNS model have then been proposed throughout the years [11][12][13][14]. As for shockwave generation, its modeling has been less adressed due to its complexity and only very recently a fully analytical model has been proposed [15].…”

Section: Introductionmentioning

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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