Yann Bouremel

Deformation of the Upper and Lower Surfaces of an Airfoil by Macro Fiber Composite Actuators

In this follow-on study, macro fiber composite actuators were used to change the shape of the upper and lower surfaces of an airfoil model with geometry close to that of a NACA 0014. In the design discussed, these thin and light piezoelectric actuators are bonded to the inside and become an integral part of the skin of the upper and lower surfaces of the airfoil. Still-air and wind-tunnel measurements in different flow regimes were performed to assess the characteristics of the static changes of the shape of the airfoil. The results obtained can be used to design a wing with morphing surfaces for improving its aerodynamics, for maneuvering without ailerons, and/or for active control of the flow over the wing.

Shape Change of the Upper Surface of an Airfoil by Macro Fiber Composite Actuators

Macro fiber composite actuators are used to displace inward or outward the upper surface of a NACA 4415 airfoil model. In the design discussed, these thin and light piezoelectric actuators are bonded to the inside and become an integral part of the skin of the upper-surface. Still-air and wind-tunnel measurements in different flow regimes were performed to assess the characteristics of static changes of the shape of the upper surface. The results obtained can be used to design a wing with morphing upper surfaces for improved aerodynamics, for maneuvering without ailerons, or for active control of the flow over the wing.

Visualization of pre-set vortices in boundary layer flow over wavy surface in rectangular channel

Smoke-wire flow visualization is used to study the development of pre-set counter-rotating streamwise vortices in boundary layer flow over a wavy surface in a rectangular channel. The formation of the vortices is indicated by the vortical structures on the cross-sectional plane normal to the wavy surface. To obtain uniform spanwise vortex wavelength which will result in uniform vortex size, two types of spanwise disturbances were used: a series of perturbation wires placed prior and normal to the leading edge of the wavy surface, and a jagged pattern in the form of uniform triangles cut at the leading edge. These perturbation wires and jagged pattern induce low-velocity streaks that result in the formation of counter-rotating streamwise vortices that evolve downstream to form the mushroom-like structures on the cross-sectional plane of the flow. The evolution of the most amplified disturbances can be attributed to the formation of these mushroom-like structures. It is also shown that the size of the mushroom-like structures depends on the channel entrance geometry, Reynolds number, and the channel gap.Graphical Abstract

Deformation of The Upper Surface of An Airfoil By Macro Fiber Composite Actuators

In this follow-on study, macro fiber composite actuators are used to change the shape of the upper surface of an airfoil model with geometry close to that of the NACA 4415 type. In the design discussed, these thin and light piezoelectric actuators are bonded to the inside and become an integral part of the skin of the upper surface of the airfoil. The model used in this study incorporates some structural changes that allow a smoother shaping of the surface closer to the leading edge of the airfoil. Still-air and wind-tunnel measurements in different flow regimes are performed to assess the characteristics of the deformation of the upper surface. The results obtained can be used to design a wing with morphing upper surface for improved aerodynamics, for maneuvering without ailerons, and/or for active control of the flow over the wing.

Open-loop flow control at low Reynolds numbers using periodic airfoil morphing

© 2015 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. This paper investigates the application of a periodically deforming airfoil surface for the purpose of flow control at low Reynolds numbers. A physical model has been fabricated by bonding Macro Fiber Composite actuators to the underside of an airfoil’s suction surface. This model is actuated using a high voltage amplifier and has been tested in a closed-loop wind tunnel at Rec = 5 × 10 4 . It was found that at high enough actuation frequencies such a control technique reduces drag and simultaneously increases lift { thus achieving signif- icant improvements in performance in a flight regime notorious for poor airfoil behavior. Furthermore, by delaying the onset of stall, actuation was able to increase the maximum lift achievable by this airfoil section at Rec = 5 × 10 4 which can be of benefit to small aircraft at take-off and landing where high lift coeffcients are required.

Measurements of a symmetric airfoil morphed by macro fiber composite actuators

This study presents the geometric and aerodynamic properties of a symmetric airfoil model that uses macro fiber composite actuators to change the shape of its upper and lower surfaces. In the design discussed, these thin and light piezoelectric actuators are bonded to the inside and become an integral part of the skin of the upper and lower surfaces of the airfoil. Still-air and wind-tunnel measurements in different flow regimes are performed to assess the characteristics associated with the changes of the shape of the airfoil. The results obtained will be used to design and fabricate a wing with morphing surfaces for testing in a remote-controlled aircraft.