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Open AccessArticle

Effect of Distortion on Turbofan Tonal Noise at Cutback with Hybrid Methods

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Aerodynamics and Acoustics Department, Safran Aircraft Engines, 77550 Moissy-Cramayel, France
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CFD Team, CERFACS, 31100 Toulouse, France
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Department of Mechanical Engineering, Université de Sherbrooke, Sherbrooke, QC J1K2R1, Canada
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Department of Aerodynamics, Energetics and Propulsion, ISAE, 31400 Toulouse, France
*
Author to whom correspondence should be addressed.
This paper is an extended version of our paper published in 22nd AIAA/CEAS Aeroacoustics Conference, 2016, Paper No. 2016-2818.
Academic Editor: Marcello Manna
Int. J. Turbomach. Propuls. Power 2017, 2(3), 16; https://doi.org/10.3390/ijtpp2030016
Received: 30 March 2017 / Revised: 31 August 2017 / Accepted: 4 September 2017 / Published: 20 September 2017
New ultra high bypass ratio architectures may significantly affect the fan tonal noise of future aircraft engines. Indeed, such a noise source is supposed to be dominated by the interaction of fan-blade wakes with outlet guide vanes. However, shorter nacelles in these engines are expected to trigger an important air-inlet distortion that can be responsible for new acoustic sources on the fan blades. Full annulus simulations based on the unsteady Reynolds-averaged Navier–Stokes equations are presently used to study this effect. Simulation results show that the air-inlet distortion has a main effect in the fan-tip region, leading to a strong variation of the fan-blade unsteady loading. It also significantly modifies the shape of the fan-blade wakes and, consequently, the unsteady loading of the outlet guide vanes. Acoustic predictions based on the extension of Goldstein’s analogy to an annular duct in a uniform axial flow are presented and show that the fan sources notably contribute to the fan tonal noise. The air-inlet distortion is responsible for an increase of the noise radiated by both the fan and the outlet guide vane sources, leading to a global noise penalty of up to three decibels. View Full-Text
Keywords: fan tonal noise; inlet distortion; hybrid methods fan tonal noise; inlet distortion; hybrid methods
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Daroukh, M.; Moreau, S.; Gourdain, N.; Boussuge, J.-F.; Sensiau, C. Effect of Distortion on Turbofan Tonal Noise at Cutback with Hybrid Methods. Int. J. Turbomach. Propuls. Power 2017, 2, 16.

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