Abstract
Modern transport aircraft wings have reached near-peak levels of energy-efficiency and there is still margin for further relevant improvements. A promising strategy for improving aircraft efficiency is to change the shape of the aircraft wing in flight in order to maximize its aerodynamic performance under all operative conditions. In the present work, this has been developed in the framework of the Clean Sky 2 (REG-IADP) European research project, where the authors focused on the design of a multifunctional twistable trailing-edge for a Natural Laminar Flow (NLF) wing. A multifunctional wing trailing-edge is used to improve aircraft performance during climb and off-design cruise conditions in response to variations in speed, altitude and other flight parameters. The investigation domain of the novel full-scale device covers 5.15 m along the wing span and the 10% of the local wing chord. Concerning the wing trailing-edge, the preliminary structural and kinematic design process of the actuation system is completely addressed: three rotary brushless motors (placed in root, central and tip sections) are required to activate the inner mechanisms enabling different trailing-edge morphing modes. The structural layout of the thin-walled closed-section composite trailing-edge represents a promising concept, meeting both the conflicting requirements of load-carrying capability and shape adaptivity. Actuation system performances and aeroelastic deformations, considering both operative aerodynamic and limit load conditions, prove the potential of the proposed structural concept to be energy efficient and lightweight for real aircraft implementation. Finally, the performance assessment of the outer natural laminar flow (NLF) wing retrofitted with the multifunctional trailing-edge is performed by high-fidelity aerodynamic analyses. For such an NLF wing, this device can improve airplane aerodynamic efficiency during high speed climb conditions.
Highlights
Worldwide air passenger traffic is predicted to grow at an average 4–5% per annum over the few decades [1]
According to Europe’s vision for aviation [1], technological breakthroughs are necessary to accomplish a major step towards the environmental goals of a 75% reduction in CO2 emissions per passenger/kilometre, a 90% cut in NOx emissions, a 65% reduction of perceived aircraft noise levels
Aircraft wings are still designed with a fixed geometry fully optimized in only a few design points, which may not be so optimal for the entire flight mission
Summary
Worldwide air passenger traffic is predicted to grow at an average 4–5% per annum over the few decades [1]. Estimated benefits for a multifunctional trailing edge, retrofitting a Fowler flap, implementing wing camber-morphing reference transport aircraft (L-1011) prove the positive effects of variable camber system based on through rigid surface deflections (for lift-to-drag ratio improvement [18]) and continuous span-wise aileron-type trailing-edge surface deflections. Reporting about the research activities developed in the framework of the Airgreen project deflections (for lift-to-drag ratio improvement [18]) and continuous span-wise twist control for (running within the “Clean Sky 2” Regional Integrated Development Platform), this paper is focused root bending moments (RBM) alleviation (through the redistribution of the span-wise aerodynamic on the preliminary design of a full-scale composite multifunctional and twistable trailing-edge load [19]).
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