Nonlinear Flexibility Effects on Flight Dynamics and Control of Next-Generation Aircraft
Lead Research Organisation:
Imperial College London
Department Name: Aeronautics
Abstract
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Organisations
- Imperial College London (Lead Research Organisation)
- Technion - Israel Institute of Technology (Collaboration)
- UNIVERSITY OF LIVERPOOL (Collaboration)
- DSTL Portsdown West (Project Partner)
- Airbus (United Kingdom) (Project Partner)
- Qinetiq (United Kingdom) (Project Partner)
- BAE Systems (United Kingdom) (Project Partner)
Publications
Wang Y
(2016)
Nonlinear Modal Aeroservoelastic Analysis Framework for Flexible Aircraft
in AIAA Journal
Hesse H
(2014)
Reduced-Order Aeroelastic Models for Dynamics of Maneuvering Flexible Aircraft
in AIAA Journal
Hesse H
(2014)
Consistent Structural Linearization in Flexible Aircraft Dynamics with Large Rigid-Body Motion
in AIAA Journal
Murua J
(2012)
Assessment of Wake-Tail Interference Effects on the Dynamics of Flexible Aircraft
in AIAA Journal
Cook R
(2013)
Robust Gust Alleviation and Stabilization of Very Flexible Aircraft
in AIAA Journal
Simpson R
(2013)
Induced-Drag Calculations in the Unsteady Vortex Lattice Method
in AIAA Journal
Hesse H
(2012)
Consistent structural linearisation in flexible-body dynamics with large rigid-body motion
in Computers & Structures
Wang Y
(2015)
A method for normal-mode-based model reduction in nonlinear dynamics of slender structures
in Computers & Structures
Cesnik C
(2014)
Reexamined Structural Design Procedures for Very Flexible Aircraft
in Journal of Aircraft
Hesse H
(2016)
Dynamic Load Alleviation in Wake Vortex Encounters
in Journal of Guidance, Control, and Dynamics
Description | We have developed new strategies to support the design and analysis of aircraft with very high aspect ratio wings. They are known to have very high aerodynamic efficiency (very low drag with respect to the lift they generate) but span is currently limited to avoid very large wing deformations. In this project we have developed the most detailed numerical models to-date to quantify the response of such vehicles to a variety of situations (turbulent weather, thermals, encountering wakes of a previous vehicle, etc.) and have shown that the large deformations, when accounted for, can in fact be beneficial -- i.e., the aerodynamic loading on the vehicle reduces and the ride becomes smoother. We have also developed the associated flight control strategies, using both offline and online control algorithms, to steer, stabilize and damp unwanted vibrations on those aircraft with very flexible wings. We have demonstrated a strategy to generate online controls (Model-predictive control) using a nonlinear description of the full flexible vehicle, in which the simulation can be run sufficiently fast to feed into a real-time optimizer that decides actions to best track a predetermined manoeuvre. We have also developed strategies for mitigate the effect of gust encounters based on multiple sensors and actuators distributed through the flexible vehicle. Overall computer simulations have showed that reductions of 25% in the design loads (which implies similar reductions in structural weight) are possible using our proposed model-based control architectures. Finally, we have developed strategies to integrate our simulation approach, which deals with the full system nonlinearity, into industrial design methods, which are based on assumptions of linear behaviour. We have shown that, starting from a detailed aeroelastic (e.g. structural and aerodynamic) aircraft model, we can extract all the relevant information in a postprocessing step to construct a nonlinear flexible vehicle model to investigate both the flight mechanics performance and the response to atmospheric conditions. Importantly, we preserve the linear solutions exactly by using the normal modes of the original model to describe the nonlinear system dynamics. |
Exploitation Route | Our findings regarding the modelling features and the transient behaviour of vehicles with very flexible wings will be useful to aircraft manufacturers to seek reduction of structural weight in next-generation air vehicles with composite wings and advanced control systems. We have released our aircraft analysis software under a non-restrictive open-source license and it has been so far used, to our knowledge, to support the design of two solar-aircraft prototypes currently undergoing flight testing. In a follow-on project we are continuing to improve the predictive capabilities of this software to facilitate the nonlinear aeroelastic analysis of a variety of vehicles. The open-source license will also allow other academic groups to use the software to develop new ideas. |
Sectors | Aerospace Defence and Marine Manufacturing including Industrial Biotechology |
URL | http://www.imperial.ac.uk/aeroelastics |
Description | Following the project, we supported the UK subsidiaries of two large technology companies (Arbus Defence and Space and Facebook Ltd) in the development of solar-powered aircraft. The tools and methods developed in this project have been used to predict the in-flight dynamic behaviour of their prototype aircraft and to improve their structural and aerodynamic design. |
First Year Of Impact | 2015 |
Sector | Aerospace, Defence and Marine |
Impact Types | Economic |
Description | (ConFlex) - Control of flexible structures and fluid-structure interactions |
Amount | € 3,932,721 (EUR) |
Funding ID | 765579 |
Organisation | European Commission |
Sector | Public |
Country | European Union (EU) |
Start | 09/2017 |
End | 09/2021 |
Description | Airbus-sponsored research |
Amount | £156,000 (GBP) |
Organisation | Airbus Group |
Sector | Academic/University |
Country | France |
Start | 08/2016 |
End | 08/2019 |
Description | EPSRC Doctoral Price Award to Yinan Wang |
Amount | £50,427 (GBP) |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 09/2015 |
End | 09/2016 |
Description | EPSRC-ICASE Airbus |
Amount | £81,000 (GBP) |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 09/2016 |
End | 09/2021 |
Description | Robust- and sustainable-by-design ultra-high aspect ratio wing and airframe (RHEA) |
Amount | € 2,000,000 (EUR) |
Funding ID | 883670 |
Organisation | European Commission H2020 |
Sector | Public |
Country | Belgium |
Start | 05/2020 |
End | 05/2022 |
Description | Collaboration in Aeroelasticity and Structural Dynamics with Technion |
Organisation | Technion - Israel Institute of Technology |
Country | Israel |
Sector | Academic/University |
PI Contribution | A collaboration was started with Prof Moti Karpel, from Technion, on the development of an aeroservoelastic analysis methodology to introduce the effects of large wing deformations into the design of load control systems on very flexible (e.g. solar-powered) air vehicles. Prof Karpel visited Imperial in two occasions (in 2011 and 2012) and has been co-author of a conference paper, which is now being submitted to the AIAA Journal. Load control systems are essential in the successful design of very large aircraft, as they cut structural weight by reducing peak loads. Their design is done using aeroservoelastic models that account for structural dynamics, aerodynamics, sensor/actuators and control. For large aircraft, wings may experience large deformations under transient dynamic response. This collaboration is developing a full description of an intrinsic nonlinear theory for load analysis of very flexible wings. |
Collaborator Contribution | Prof Karpel gave a short course in aeroelasticity at Imperial and provide technical experience in the development of the theory. |
Impact | A conference paper and a software tool |
Start Year | 2011 |
Description | Collaboration with University of Liverpool |
Organisation | University of Liverpool |
Department | Institute of Integrative Biology |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | The CFD Lab at Liverpool were co-investigators in this project. We developed geometrically-nonlinear structural model suitable for high-fidelity flexible aircraft simulations, including interfacing strategies. |
Collaborator Contribution | Our colleagues at Liverpool (led by Prof Ken Badcock) integrated our models into their unsteady RANS fluid solver. As a result we were able to investigate full vehicle response and develop nonlinear reduced-order methods based on the full fidelity description. |
Impact | The main output is software and methods that are now in place at the CFD Lab in Liverpool. My colleagues there have long-standing interactions with Airbus and BAE Systems and this software is available for nonlinear simulations of aircraft response. We presented two joint papers at AIAA conferences with the details of the approach. |
Start Year | 2011 |
Title | SHARPy: Simulation of High-Aspect-Ratio aircraft and wind turbines in Python |
Description | Nonlinear and dynamically linearized models of very flexible aircraft dynamics for design, analysis, and control law synthesis. |
Type Of Technology | Software |
Year Produced | 2014 |
Open Source License? | Yes |
Impact | It has been used in the aerodynamic and structural design of Facebook's Aquila, Airbus's Zephyr and Astigan Ltd's solar-powered aircraft. |
URL | http://www.imperial.ac.uk/aeroelastics/sharpy |
Description | Interview at BBC World Service |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | Interview to Dr Palacios at BBC Click |
Year(s) Of Engagement Activity | 2016 |
URL | http://www.bbc.co.uk/programmes/p03jpn3t |