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Thèse Johannes Scheller

9 octobre 2015

Electroactive morphing for the aerodynamic performance improvement of next generation airvehicles

Thèse Johannes Scheller

Mardi 20 octobre - Amphithéâtre Nougaro à 14 h 30

Sous réserve d’autorisation de soutenance par les rapporteurs

Abstract :

The need to improve the aerodynamic performance of air vehicles is the origin of intense research on the real-time optimization of the airfoil shape. This real-time optimization can only be achieved by morphing the airfoil using adequate materials and actuators. The object of this thesis is to study smart-material actuators for aerodynamic performance optimization on different time scales (low-frequent and high-frequent actuation).
First, the effects of the distinct actuation types, low-frequency large-displacement shape-memory alloy (SMA) and high-frequency low-displacement piezoelectric, on the surrounding flow are analyzed separately using dedicated particle image velocimetry (PIV) measurements. The experiments showed the deformation capacity of the SMA technology under realistic aerodynamic loads. Furthermore, it was highlighted that despite the limited actuation frequency the “quasi-static” hypothesis has to be carefully adapted for the Reynolds number range of 200.000. The PIV measurements conducted behind the piezoelectrically actuated trailing edge showed the capacity of the actuator to reduce the shear-layer instability modes. An open-loop optimum actuation frequency of 60 Hz has been identified. Secondly, a hybridization of the two previously studied technologies has been proposed. The implied actuators, SMAs and macro fiber composites (MFCs), have been modelled and the combined actuation capacity has been demonstrated. The designed prototype NACA4412 airfoil has been tested in the windtunnel and it was shown that the combination of the two technologies allows to act on the shear-layer vortices as well as control the lift.

Composition de jury :

Jean-François Rouchon - Directeur de thèse

Marianna Braza - Directrice de Thèse

Eric Duhayon

Jean-Paul Bonnet - Rapporteur

Lionel Petit - Rapporteur

Julian Hunt

Michael Triantafyllou

et membres invites :

Christophe Cros

Yann Doutreleau