Aeroelastic Stability Analysis of a Wind Tunnel Wing Model Equipped with a True Scale Morphing Aileron

Abstract

In last decades, several research programs were founded worldwide to exploit the potentialities of the morphing concepts, especially to improve aerodynamic efficiency, and so reduce fuel consumption. Among these, the CRIAQ MDO-505 project represents the first joined research program between Canadian and Italian academies, research centers and leading industries. The aim of the project is to design, manufacture and tests in wind tunnel facilities a morphing wing tip for a Bombardier-type aircraft controlled by electric actuators and pressure sensors. In such framework, the authors intensively worked on the flutter clearance demonstration of the wind tunnel wing model equipped with a full-scale variable-camber aileron driven by load-bearing electro-mechanical actuators. Rational approaches were implemented in order to simulate the effects induced by variations of aileron actuator's stiffness on the aeroelastic behavior of the wing. Reliable models were properly implemented to enable fast aeroelastic analyses covering several configuration cases in order to prove clearance from any dynamic instability (flutter) up to 1.2 times the maximum flow speed expected during Wind Tunnel Tests. Finite-element models were properly developed in order to obtain and implement wing model modal parameters (modes shapes, frequencies, generalized masses, damping) in SANDY®, an in-house developed code, that was used for the definition of the coupled aerostructural model as well as for the solution of aeroelastic stability equations by means of theoretical modes association in frequency domain. Obtained results were finally arranged in a diagram showing trend of the flutter speed with respect to changes in control surface harmonic covering a wide range of values for the stiffness of the aileron (external) actuator.  Index Terms-morphing aileron, aeroelasticity, flutter, aeroelastic stability, variable camber, active ribs, smart structures, FEM.I.

Recent developments in the aeroelasticity of morphing aircraft

“…Moreover, the proper balancing of the trailing edge could avoid flutter instability within the flight envelope. Rea et al [129] conducted an aeroelastic stability analysis of a wind-tunnel model equipped with a full-scale morphing aileron driven by load-bearing electromechanical actuators. The aim of their study was to prove that the concept is free from flutter up to 1.2 times the maximum expected flow speed (85m/s) during planned wind-tunnel tests.…”