Daniel Coutu

Design of Shape Memory Alloy Actuators for Morphing Laminar Wing With Flexible Extrados

An active structure of a morphing wing designed for subsonic cruise flight conditions is composed of three principal subsystems: (1) fexible extrados, (2) rigid intrados, and (3) an actuator group located inside the wing box. The four-ply laminated composite flexible extrados is powered by two individually controlled shape memory alloy (SMA) actuators. Fulfilling the requirements imposed by the morphing wing application to the force-displacement characteristics of the actuators, a novel design methodology to determine the geometry of the SMA active elements and their adequate assembly conditions is presented. This methodology uses the results of the constrained recovery testing of the selected SMA. Using a prototype of the morphing laminar wing powered by SMA actuators, the design approach proposed in this study is experimentally validated.

Morphing laminar wing with flexible extrados powered by shape memory alloy actuators

An active structure of a morphing wing designed for subsonic cruise flight conditions combines three principal subsystems: (1) flexible extrados, (2) rigid intrados and (3) an actuator group located inside the wing box. A structural model of the flexible extrados built with ANSYS finite element software is coupled with X’Foil fluid dynamics software to evaluate mechanical and aerodynamic performances of the morphing wing in different flight conditions. Using the multicriteria optimization technique, an active structure consisting of the 4-ply laminated composite flexible extrados powered by two individually controlled actuators is selected. Shape memory alloy (SMA) actuators are designed as power elements for the morphing wing. To meet the functional requirements of the application, the geometry of the SMA elements is calculated using the results of the constrained recovery testing of the selected material.Copyright

Aerostructural Model for Morphing Laminar Wing Optimization in a Wind Tunnel

An aerostructural numerical model of a two-dimensional morphing laminar wing prototype is built and validated for different flight conditions: Mach numbers ranging from 0.2 to 0.3 and angles of attack ranging from -1 to 2C. The active structure of the wing is modeled using the ANSYS commercial finite element software. The aerostructural interaction is achieved by coupling the XFoil free-license aerodynamic solver to ANSYS. This model is used to minimize the drag force under constant-lift conditions during wind-tunnel testing using a two-step optimization algorithm (global and local search). The wake pressure wind-tunnel measurements show that extrados morphing results in an average 18.5% drag reduction for eight flow cases covering the flow condition range of interest. Simultaneously, the infrared thermography measurements record an average laminar flow extension of 25% of the wing chord over the upper wing surface. The experimental and numerical results are in good agreement, thus validating the use of an aerostructural model to efficiently manage the shape of a morphing laminar wing.

Lift-to-drag ratio and laminar flow control of a morphing laminar wing in a wind tunnel

A new hardware-in-the-loop control strategy to enhance the aerodynamic performance of a two-dimensional morphing laminar wing prototype was developed and tested. The testing was performed in a wind tunnel under cruise flight flow conditions: Mach number ranging from 0.2 to 0.3 and angle of attack from − 1° to 0.5°. For each set of flow conditions, the shape of the upper surface of the wing was modified using two independent shape memory alloy actuators. The wing shape was morphed in two sequential steps. The initial morphed shape was controlled using open-loop architecture and the results of an anterior aero-structural numerical optimization study. The final morphed shape was closed-loop controlled using either the wind tunnel balance or an infrared camera as hardware-in-the-loop to give an instantaneous lift-to-drag ratio (L/D) or a laminar flow extension (xtr/c) over the upper surface of the prototype. In respect to the aerodynamic performance of the unactuated wing profile, the L/D gain varies from 10.6 to 15% for the closed-loop control strategy compared to 10.0 to 13.7% for the open-loop control strategy. Laminar flow extension gains, Δxtr/c, measured by infrared camera, were situated in the 29–33% range for both control strategies. However, the results obtained showed that the closed-loop controller could be hindered by the noise of the hardware-in-the-loop signal.

Real-Time Optimization of a Research Morphing Laminar Wing in a Wind Tunnel

This paper presents a new approach of real-time control of a morphing wing based on a coupled fluid-structure numerical model. The 2D extrados profile of an experimental laminar wing is morphed with the purpose to reduce drag, through extension of the laminar flow over the upper wing surface. As a first step, the active structure has been modeled, manufactured and experimentally tested under variable flow conditions in a subsonic wind tunnel (the Mach number ranges from 0.2 to 0.3 and the angle of attack from −1° to 2°). In this work, a real-time closed-loop control strategy is designed to find the optimum actuator strokes using an experimentally measured lift-to-drag ratio (feedback parameter). An extensive wind-tunnel characterization of the laminar wing prototype has been performed to design the algorithm and to set up the parameters. To calculate the initial strokes of the actuators and thus to accelerate the optimization procedure, a validated ANSYS-XFoil coupled fluid-structure numerical model is used. The robustness and efficiency of the developed real-time control system is tested under two flow conditions. The morphing wing performance obtained is slightly superior or similar to the open loop control approach proving the high performance of the numerical model. The proposed control strategy appears to be well suited to benefit from the complete morphing potential (according to the lift-to-drag ratio) of the wind tunnel prototype although higher feedback resolution is recommended from the numerical simulation algorithms.Copyright

Wind-Tunnel Testing of Shape Memory Alloys Actuators as Morphing Wing Driving Systems

A morphing wing, composed of flexible extrados, rigid intrados and a Shape Memory Alloys (SMA) actuator group located inside the wing box, is used to adapt an airfoil profile to variable flight conditions. The SMA actuator group developed for the morphing wing prototype consists of three main subsystems: the SMA active element, the transmission system, and the passive bias element. The functional requirements for the actuator group were determined using a coupled fluid-structure model of the flexible extrados. An original design approach was applied to determine the geometry and assembly conditions of the SMA active elements. For validation purposes, the morphing wing powered by SMA actuators was tested in a wind tunnel under subsonic flight conditions (Mach = 0.2 to 0.3 and α = −1 to 2°). The ability of the actuator group to move the flexible extrados up to 8 mm of vertical displacement and to bring it back to the initial profile has been successfully proven for all of the wind tunnel testing conditions. During the repetitive actuation, the force, displacement and temperature of the SMA active elements were measured and the results obtained in the force-displacement-temperature space were used to validate the SMA performances predicted during the design phase.Copyright