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Modifications des tourbillons d'extrémité d'hélices contra-rotatives en vue d'une réduction des nuisances sonores

Abstract : This thesis is concerned with noise reduction of Counter-Rotating Open Rotor (CROR). We are particularly interested in vortical structures shed by the front propeller blades which impact the rear blades. The goal of the thesis is to investigate the possibility to modify these structures in order to reduce the noise produced by this interaction during take-off. The first part is devoted to their characterization, using the HTC5 baseline CROR geometry designed by Onera. First, the physics of wake formation is described using numerical tools. Then the main part of the study is carried out on a non-rotating blade that reproduces the radial circulation distribution of a front rotating HTC5 propeller blade. Thanks to an experimental investigation of this fixed blade, the vortex properties are determined and the numerical methodology is assessed. This step finally leads to the definition of an analytical model describing this vortex. The second part of the thesis is dedicated to the modification of these vortical structures. First, an application of concepts existing in the literature is realized on the fixed blade in order to estimate their impact on vortices. Using these results, a new concept to modify vortical structures is defined: a blade leading-edge protuberance. This aim of this concept is to generate a system of two co-rotating vortices separated by counter-rotating vorticity. The physics of the interaction between the two vortices is studied in this thesis. Finally, the acoustic benefits of this concept are assessed on the HTC5 CROR configuration.
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https://pastel.archives-ouvertes.fr/pastel-00843556
Contributor : Laurence Vion <>
Submitted on : Thursday, July 11, 2013 - 4:26:53 PM
Last modification on : Thursday, February 27, 2014 - 1:40:50 PM
Long-term archiving on: : Wednesday, April 5, 2017 - 9:54:19 AM

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Laurence Vion. Modifications des tourbillons d'extrémité d'hélices contra-rotatives en vue d'une réduction des nuisances sonores. Mécanique des fluides [physics.class-ph]. Ecole Polytechnique X, 2013. Français. ⟨pastel-00843556⟩

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