Optimization and design of an aircraft's morphing wing-tip demonstrator for drag reduction at low speeds, Part II - Experimental validation using Infra-Red transition measurement from Wind Tunnel tests

In the present paper, an ‘in-house’ genetic algorithm was numerically and experimentally validated. The genetic algorithm was applied to an optimization problem for improving the aerodynamic performances of an aircraft wing tip through upper surface morphing. The optimization was performed for 16 flight cases expressed in terms of various combinations of speeds, angles of attack and aileron deflections. The displacements resulted from the optimization were used during the wind tunnel tests of the wing tip demonstrator for the actuators control to change the upper surface shape of the wing. The results of the optimization of the flow behavior for the airfoil morphing upper-surface problem were validated with wind tunnel experimental transition results obtained with infra-red Thermography on the wing-tip demonstrator. The validation proved that the 2D numerical optimization using the ‘in-house’ genetic algorithm was an appropriate tool in improving various aspects of a wing’s aerodynamic performances

A new non-linear vortex lattice method : applications to wing aerodynamic optimizations

This paper presents a new non-linear formulation of the classical Vortex Lattice Method (VLM) approach for calculating the aerodynamic properties of lifting surfaces. The method accounts for the effects of viscosity, and due to its low computational cost, it represents a very good tool to perform rapid and accurate wing design and optimization procedures. The mathematical model is constructed by using two-dimensional viscous analyses of the wing span-wise sections, according to strip theory, and then coupling the strip viscous forces with the forces generated by the vortex rings distributed on the wing camber surface, calculated with a fully three-dimensional vortex lifting law. The numerical results obtained with the proposed method are validated with experimental data and show good agreement in predicting both the lift and pitching moment, as well as in predicting the wing drag. The method is applied to modifying the wing of an Unmanned Aerial System to increase its aerodynamic efficiency and to calculate the drag reductions obtained by an upper surface morphing technique for an adaptable regional aircraft wing

Improving the UAS-S4 Ehecatl airfoil high angles-of-attack performance characteristics using a morphing wing approach

In this paper, a morphing wing approach with a new methodology and its results for the high angles-of-attack optimization of the S4 unmanned aerial system airfoil are described. The boundary layer separation delay, coupled with an increase of the maximum lift coefficient, was achieved using an in-house optimization tool based on the artificial bee colony algorithm, coupled with the Broyden–Fletcher–Goldfarb–Shanno algorithm to provide a final refinement. The obtained results were validated with an advanced, multi-objective, commercially available optimizing tool. The aerodynamic calculations were performed using a two-dimensional linear panel method, coupled with an incompressible boundary layer model and a transition estimation criterion. For very small displacements of the airfoil surface, of less than 2.5 mm, lift coefficient increases of up to 18% together with relevant drag reductions have been achieved, successfully delaying separation for the high angles-of-attack range

Numerical simulation and wind tunnel tests investigation and validation of a morphing wing-tip demonstrator aerodynamic performance

This paper presents the results obtained from the numerical simulation and experimental wind tunnel testing of a morphing wing equipped with a flexible upper surface and controllable actuated aileron. The technology demonstrator is representative of a real aircraft wing tip section, and it was developed following a complex, multidisciplinary design process. The model was fitted with a composite material upper skin whose shape can be morphed, as a function of the flight condition, by four electrical actuators placed inside the wing structure. The optimizations were performed with the aim of controlling the extent of the laminar flow region, and the resulting shapes were scanned using high-precision photogrammetry. The numerical simulations were performed using Computational Fluid Dynamics (CFD) and included a model for predicting the laminar-to-turbulent flow transition over the entire wing surface. The analyses included cases with three aileron deflection angles and angles of attack situated within five degrees range. The CFD results were compared with infrared thermography measurements in terms of transition location, surface pressure measurements and balance loads measurements acquired during subsonic wind tunnel tests performed at the National Research Council Canada