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Accueil du site > Évènements > Séminaires > Séminaires IUSTI > Archives IUSTI > 2015

Vendredi 13 Février 2015 / IUSTI

publié le

Séminaire IUSTI

Closed-loop experiments to identify the separated flow dynamics of a thick turbulent boundary layer

Orateur : Caroline Braud
Laboratoire de Mécanique de Lille, Université de Lille 1

Résumé : In the last few decades many different flow control configurations (flat plates, ramps, bumps, ducts, airfoils, wind turbines, etc.) were investigated in order to delay or prevent turbulent boundary layer separation. At first, passive devices such as small plates of different shapes (rectangular, triangular, etc.) inclined relatively to the free-stream velocity, often referred as Vortex Generators (VG), were mounted on the wall to generate streamwise vortices. They were later replaced by devices embedded in the inner log region as they provided similar efficiency with notably less drag penalty at cruise conditions. To adapt the control to a given flow configuration and to be able to switch it off when it is not required, passive devices were rapidly replaced by active ones, which can be dynamically operated. Recently, operating parameters of active devices were used as input variables in various closed-loop designs. In the present study, the closed-loop was applied to a high Re turbulent boundary layer, under a weak adverse pressure gradient, which separates after a sharp variation of the geometry of the ramp. From this experiment it was possible to extract the dynamics of the attachment/separation process, which can be reduced to a first order linear ODE system.

Date et lieu : le Vendredi 13 Février 2015 à 11h00, salle 250 IUSTI