High Bandwidth Morphing Aerofoil

Abstract

This paper presents the experimental development of a morphing aerofoil which has a dual goal of controlling flight mechanics and increasing flutter speed, both by active control of the aeroelastic wing designed as part of the project. In order to achieve these aims, the static camber variation of the aerofoil, as well as its actuation bandwidth, have to be sufficiently high. The morphing aerofoil sector is a NACA 0018 with a chord of 300 mm and a final span of 250 mm (however the preliminary test sector has a span of 40 mm). The non-deformable part of the sector is 3D printed in ABS and the active camber deformation is achieved by bonding to the trailing edge portion of the structure tailored (MFC) piezo-patch-sandwiches properly actuated by ad hoc high-voltage amplifiers. A linear trailing edge slider is used to allow the necessary skin deformation. A PID inner control layer on the tip displacement feedback is developed in a real-time environment using a laser displacement sensor. The preliminary design of the model, as well as the static and dynamic experimental tests on the prototype, is illustrated and discussed in the paper. A comparison with a traditional control surface aerofoil of same size is also be provided. For this purpose, low fidelity numerical calculations and CFD is used. A brief contextualization of this work within the aeroelastic wing project is presented. The morphing sector is one of four sectors which compose the aerodynamic shape of a flexible wing, with a 1 m span and 300 mm chord, designed to have the first bending and torsion mode frequencies lower than 10 Hz and a linear flutter speed around 15 m/s. This rig has the objective of providing experimental benchmarks for testing algorithms for linear/nonlinear aeroelastic control phenomena