Tonal Noise Prediction of a Modern Turbofan Engine With Large Upstream and Downstream Distortion

Daroukh, Majd; Moreau, Stéphane; Gourdain, Nicolas; Boussuge, Jean‐François; Sensiau, Claude

doi:10.1115/1.4042163

Cited by 22 publications

(13 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A recent alternative, better suited for the identification of acoustic phenomena at particular frequencies, is the Dynamic Mode Decomposition (DMD) [31], a technique which aims to group coherent spatial features into modes of a single temporal frequency [32,33]. It has been used in recent investigations of, for instance, cavity flow [34], airfoil buffeting [35], fan [36] combustion [37,38] and landing gear [39] noise, and turbocharger acoustics [40,41], among others.…”

Section: Dynamic Mode Decompositionmentioning

confidence: 99%

Dynamic mode decomposition of the acoustic field in radial compressors

Broatch

García-Tíscar

Roig

et al. 2019

Aerospace Science and Technology

View full text Add to dashboard Cite

Widely recognized since the beginning of air travel as a major issue, noise reduction remains nowadays a pressing concern for all stakeholders in the aviation industry. While aeroengine compressors, specially at the approach phase, have been historically identified as a leading source of noise, most of the research has been conducted on compressors of the axial type. However, radial compressors are found in a wide array of applications: smaller business jets, helicopters, unmanned aerial vehicles (UAVs), auxiliary power units (APUs), turbochargers for reciprocating engines, etc. Owing to their geometrical particularities, radial compressors feature flow patterns that differ from their axial counterparts, leading to different acoustic performance but also opening the door for different optimization approaches. Yet, classical modal decomposition techniques focused on duct propagation may fail to reveal the complex interactions between geometry and flow features that act as noise sources. In this paper we apply, in addition to the classical approach, a data-driven Dynamic Mode Decomposition (DMD) to pressure data coming from a Detached Eddy Simulation (DES), in which we have experimentally validated the correct reproduction of the modal behaviour of the compressor, thus obtaining in-depth details of the link between flow phenomena and noise generation and transmission across the inlet and outlet ducts.

show abstract

Section: Dynamic Mode Decompositionmentioning

confidence: 99%

Dynamic mode decomposition of the acoustic field in radial compressors

Broatch

García-Tíscar

Roig

et al. 2019

Aerospace Science and Technology

View full text Add to dashboard Cite

show abstract

“…Several recent studies have therefore focused on the impact of distortion on the noise emitted by turbofan engines [1][2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…They have shown that the tone noise characteristics can be significantly modified by: (a) introducing new acoustic sources caused by the distortion/fan blades interaction [3,4,8], (b) modifying the conventional fan-blade wakes/Outlet…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

2020

View full text Add to dashboard Cite

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

show abstract

“…This is typically the case during landing or take-off operations (angle of attack around 10°-15°) where airport neighbours are the most exposed to noise nuisance. Several recent studies have therefore focused on the impact of distortion on the noise emitted by turbofan engines [1][2][3][4][5][6][7][8]. They have shown that the tone noise characteristics can be significantly modified by: (a) introducing new acoustic sources caused by the distortion/fan blades interaction [3][4][5], (b) modifying the conventional fan-blade wakes/Outlet Guide Vanes (OGVs) interaction [3][4][5]8], and (c) modifying the generation and propagation of fan-blade shocks at transonic speeds [1][2][3][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Shockwave Generation and Radiation from an UHBR Engine with Flow Distortion Using a CFD/CAA Chaining Strategy

Daroukh¹,

Polacsek²,

Chelius³

2019

25th AIAA/CEAS Aeroacoustics Conference

Self Cite

View full text Add to dashboard Cite

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. The shocks are then radiated outside of the nacelle thanks to Computational AeroAcoustics (CAA) simulations. The same solver is used for both CFD and CAA simulations and the chaining 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 shock propagation mechanisms are investigated and the effects of inflow distortion are highlighted by comparison with a baseline case without distortion. It is shown that the distortion, characterized by an acceleration of the flow at the bottom of the nacelle, is responsible for a modification of the shock amplitudes that depends on the circumferential position. Thus, azimuthal modes appear in addition to the rotor-locked mode present without distortion. The near-field radiation is also highly impacted with most of the noise being directed towards the sky. This is due to the blockage of shocks by a supersonic flow region in the bottom of the nacelle. The radiation is in addition highly heterogeneous in the other directions because of the various angles of the shocks that leave the nacelle.

show abstract

Tonal Noise Prediction of a Modern Turbofan Engine With Large Upstream and Downstream Distortion

Cited by 22 publications

References 26 publications

Dynamic mode decomposition of the acoustic field in radial compressors

Dynamic mode decomposition of the acoustic field in radial compressors

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

Shockwave Generation and Radiation from an UHBR Engine with Flow Distortion Using a CFD/CAA Chaining Strategy

Contact Info

Product

Resources

About