[Contrôle du décollement autour dʼun profil dʼaile présentant un bord dʼattaque ondulé inspiré des ailerons de la baleine à bosse]
Lʼinfluence dʼondulations géométriques le long du bord dʼattaque dʼun profil dʼaile est étudiée numériquement à faible nombre de Reynolds, dans une optique de contrôle passif du décollement et en se focalisant sur les mécanismes physiques mis en jeu. Inspiré des tubercules présents sur les ailerons des baleines à bosse, ce bord dʼattaque ondulé est modelisé par une sinusoïde le long de lʼenvergure, dont la longueur dʼonde et lʼamplitude constituent les paramètres de contrôle. Une simulation numérique directe est effectuée sur un profil NACA0020 dans une configuration dʼécoulement décroché (), avec et sans ondulation de bord dʼattaque. Les frontières solides complexes engendrées par la variation des paramètres de lʼondulation géométrique sont traitées par la méthode des frontières immergées (IBM). Les noyaux des opérateurs dʼinterpolation/diffusion sont construits en utilisant la méthode RKPM (Pinelli et al., 2010 [12]). Une étude paramétrique permet dʼextraire un jeu de paramètres dʼondulation qui amène à une modification significative de la topologie de lʼécoulement décollé, qui se retrouve dominé par des tourbillons orientés vers lʼaval et générés sur les cotés des protubérances de bord dʼattaque. Une analyse physique est menée pour expliquer le mécanisme de formation de ces structures cohérentes tourbillonnaires. Le rôle quʼelles jouent dans le contrôle du décollement de couche limite est étudié également, sous lʼéclairage des modifications de performances hydrodynamiques présentées dans la litterature au cours de la dernière décennie.
The influence of spanwise geometrical undulations of the leading edge of an infinite wing is investigated numerically at low Reynolds number, in the context of passive separation control and focusing on the physical mechanisms involved. Inspired by the tubercles of the humpback whale flippers, the wavy leading edge is modeled using a spanwise sinusoidal function whose amplitude and wavelength constitute the parameters of control. A direct numerical simulation is performed on a NACA0020 wing profile in a deep stall configuration (), with and without the presence of the leading edge waviness. The complex solid boundaries obtained by varying the sinusoidal shape of the leading edge are modeled using an immersed boundary method (IBM) recently developed by the authors [Pinelli et al., J. Comput. Phys. 229 (2010) 9073–9091]. A particular set of wave parameters is found to change drastically the topology of the separated zone, which becomes dominated by streamwise vortices generated from the sides of the leading edge bumps. A physical analysis is carried out to explain the mechanism leading to the generation of these coherent vortical structures. The role they play in the control of boundary layer separation is also investigated, in the context of the modifications of the hydrodynamic performances which have been put forward in the literature in the last decade.
Mot clés : Contrôle dʼécoulements, Biomimétisme, Méthode des frontières immergées, Ailerons de baleines à bosse
@article{CRMECA_2012__340_1-2_107_0,
author = {Julien Favier and Alfredo Pinelli and Ugo Piomelli},
title = {Control of the separated flow around an airfoil using a wavy leading edge inspired by humpback whale flippers},
journal = {Comptes Rendus. M\'ecanique},
pages = {107--114},
publisher = {Elsevier},
volume = {340},
number = {1-2},
year = {2012},
doi = {10.1016/j.crme.2011.11.004},
language = {en},
}
TY - JOUR AU - Julien Favier AU - Alfredo Pinelli AU - Ugo Piomelli TI - Control of the separated flow around an airfoil using a wavy leading edge inspired by humpback whale flippers JO - Comptes Rendus. Mécanique PY - 2012 SP - 107 EP - 114 VL - 340 IS - 1-2 PB - Elsevier DO - 10.1016/j.crme.2011.11.004 LA - en ID - CRMECA_2012__340_1-2_107_0 ER -
%0 Journal Article %A Julien Favier %A Alfredo Pinelli %A Ugo Piomelli %T Control of the separated flow around an airfoil using a wavy leading edge inspired by humpback whale flippers %J Comptes Rendus. Mécanique %D 2012 %P 107-114 %V 340 %N 1-2 %I Elsevier %R 10.1016/j.crme.2011.11.004 %G en %F CRMECA_2012__340_1-2_107_0
Julien Favier; Alfredo Pinelli; Ugo Piomelli. Control of the separated flow around an airfoil using a wavy leading edge inspired by humpback whale flippers. Comptes Rendus. Mécanique, Volume 340 (2012) no. 1-2, pp. 107-114. doi : 10.1016/j.crme.2011.11.004. https://comptes-rendus.academie-sciences.fr/mecanique/articles/10.1016/j.crme.2011.11.004/
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