Design, Manufacturing and Wind Tunnel Validation of a Morphing Compliant Wing

Abstract

The paper describes the activities performed at Politecnico di Milano in the framework of FP7-NOVEMOR Project aiming at the design, manufacturing and wind tunnel test of a wing model equipped with morphing leading and trailing edges based on compliant structures. Starting from the Reference Aircraft, i.e. a typical regional aircraft developed during NOVEMOR project, a small scale wind tunnel model has been derived to validate the proposed morphing concept and to correlate the numerical models in an experimental environment. A special attention has been devoted to the selection of the manufacturing technology due to the difficulty in realizing compliant structures with enough accuracy at a small scale level. After a short reminder of the tools developed for the design of variable camber morphing wings, the paper describes in details the design and manufacturing phases together with the functionality and wind tunnel tests.The results were used to validate the procedure adopted for the synthesis of the compliant structures and to evaluate the aerodynamic performances of the morphing wing. Nomenclature a = vector of CST extra-coefficients α = angle of attack [deg] α e = "effective" angle of attack [deg] c = airfoil chord [m] C d = drag coefficient for unit span C l = lift coefficient for unit span C m = pitch moment coefficient for unit span ∆κ = curvature difference function between the initial and the deformed shape [1/m] ∆L = length difference function between the initial and the deformed shape [m] δ LE = leading edge equivalent deflection [deg] δ T E = trailing edge equivalent deflection [deg] ψ = non-dimensional airfoil chordwise coordinate T p = CST-Vandermonde matrix of order p σ axial = axial stress due to the skin length variation [Pa]σ bend = bending stress due to the skin curvature variation [Pa]

Aerodynamic Shape Design and Validation of an Advanced High-Lift Device for a Regional Aircraft with Morphing Droop Nose

“…Starting from the studies carried out during the participation to previous EU projects, such as SARISTU and NOVEMOR [17,18], the optimal morphing droop nose has been designed to be installed on the Green Regional Aircraft, in terms of both external morphing shape and internal compliant mechanism [19,20]. In this manuscript, only the dedicated shape optimization process, adopted for the aerodynamic shape design of the complete high-lift device, is described starting from the "clean" NLF wing geometry.…”

“…Once the shape of the NLF wing is defined, it can be used to introduce the shape changes due to the morphing only in high-lift conditions, together with the configuration changes due to the flap deployment. Previous works in the scientific literature show that the aerodynamic evaluation of a morphing droop nose, optimized for low-speed conditions, must be performed considering the wing in its high-lift configuration [18]. For this reason, the shape design of the flap is performed before.…”

Comparison of Constrained Parameterisation Strategies for Aerodynamic Optimisation of Morphing Leading Edge Airfoil

“…The morphing leading edge concept has received a fair amount of attention from the scientific community in the past few years, and has been investigated in several European projects like SADE [9,10], SARISTU [11], NOVEMOR [12], LeaTop [13], and the Green Regional Aircraft platform of Clean Sky [14], where structural optimisation, material selection, actuation mechanism design, and integration aspects were assessed. In fact, despite the fact that the main reason to employ this technology is the potential aerodynamic benefit, structural issues represent the main challenge for its adoption.…”

Morphing Wing Droop Nose with Large Deformation: Ground Tests and Lessons Learned

“…A conceptual numerical study on a variable stiffness skin by means of continuously variable ply angles as opposed to variable-thickness-laminates is presented in [21]. Wind tunnel tests of a flexible wing leading edge with compliant mechanisms are presented in [22,23] and additional compliant mechanism designs are presented in [24]. A morphing droop nose with a stretchable skin based on carbon nanotube-polyurethane sheets is described in [25].…”