TOWARDS BIOLOGICALLY-INSPIRED ACTIVE-COMPLIANT-WING MICRO-AIR-VEHICLES

Natural fliers achieve exceptional aerodynamics by continuous adjustments on their geometry through a mix of dynamic wing compliance and distributed sensing and actuation. This enables them to routinely perform a wide range of manoeuvres including rapid turns, rolls, dives, and climbs with seeming ease. Despite a good knowledge of the physiology of bats and birds, engineering applications with active dynamic wing compliance capability are so far few and far-between. Recent advances in development of electroactive materials together with high-fidelity numerical/experimental methods provide a foundation to develop biologically-inspired dynamically-active wings that can achieve "on-demand" aerodynamic performance. However, this requires first to develop a thorough understanding of the dynamic coupling between the electro-mechanical structure of the membrane wing and its unsteady aerodynamics. In this collaborative initiative between the University of Southampton and Imperial College London, we will develop an integrated research programme that carries out high-fidelity experiments and computations to achieve a fundamental understanding of the dynamics of aero-electro-mechanical coupling in dynamically-actuated compliant wings. The goal is to utilise our understanding and devise control strategies that use integral actuation schemes to improve aerodynamic performance of membrane wings. The long-term goal of this project is to enable the use of soft robotics technology to build integrally-actuated wings for Micro Air Vehicles (MAV) that mimic the dynamic shape control capabilities of natural flyers.

Birds can soar on thermals, hover above prey, land on water, and generate power through wing flapping, among many other things. One by one, these abilities have been achieved by man-made designs, yet there is a fundamental biological feature of birds that engineers have not been able to master so far: the ability to change wing shape in a continuous and controlled manner. This has long been an aspiration of aeronautics as it would provide huge gains in aerodynamic efficiency and manoeuvrability.

This research proposes a combined approach through high-fidelity simulations and experiments to tackle this challenge. It will combine the state of the art in artificial muscle technology with high-performance computational modelling to carry out the first ever attempt at investigating the dynamic interactions between a fluid and an integrally-actuated membrane wings.

In addition to the new tools and methodologies, the project will obtain (numerically and experimentally) high-fidelity results of separated flow over deforming membranes. They are also expected to be of great importance on their own since new validated data will be made available to the aeronautics community that is currently not available.

The target application is wing shape control on micro-air-vehicles and a proof of concept will be built with that in mind, but the methodologies and the technology will find more general applications in the development of new active flow control devices and in the modelling of complex problems in multiphysics. In particular, we expect that the numerical tools will find applications in the modelling of biological flows, micropumps or fluidic actuators, among others. We also foresee that active flow control approaches based on actuated membranes will eventually be integrated in larger structures, such as wind turbine blades or wings of transport aircraft. The basic technology required for the development of such applications would be a direct evolution of those developed in this project.