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Smart Morphing and Sensing

Periodic Reporting for period 2 - SMS (Smart Morphing and Sensing)

Reporting period: 2018-11-01 to 2020-04-30

The Smart Morphing & Sensing (SMS) project is a multi-disciplinary upstream project that employs intelligent electro-active actuators that will modify the lifting structure of an aircraft and to obtain the optimum shape with respect to the aerodynamic performance (high lift & low drag). This will be accomplished using a new generation of fiber optics based sensors allowing distributed pressure measurements and in-situ real-time optimisation of the aerodynamic characteristics. This will allow to attenuation of flow separation and nuisance instabilities such as aileron flutter and also to reduce trailing-edge noise and other vibration sources in flight, coming from interactions between wing and fuselage and engine or from critical meteorological phenomena as gusts, having major impact on safety. The SMS project associates the following methods that will be coupled in a multi-disciplinary environment:
1. Advanced integrated aeroelastic design using High-Fidelity CFDSM (Computational Fluid Dynamics-Structural Mechanics)
2. Advanced distributed sensing using a new generation of high-fidelity fiber optics sensors
3. Advanced experimental techniques to provide data together with the high-fidelity simulations for the iterative feedback of the controller design to be used for the optimisation of the morphing flap of an A320 type wing. These experimental techniques will also be used as a basis for the validation of both the novel actuation and sensing systems via wind tunnel tests at subsonic (take-off and landing) and transonic (cruise) speeds.
4. Controller Design by appropriate Flight Control Commands (FCC), to actuate the electro-active materials properties in order to enable a real-time in-situ optimisation of the final prototypes in reduced scale and large scale.
5. The SMS project is unique thanks to its strong multidisciplinary character and degree of innovation.
Importance for the Society:
These objectives will be achieved by the new morphing devices operating in dynamic regimes and enabled by novel sensing devices. This smart morphing-sensing system will be actuated by an efficient controller design achieved by a suitable interface of control commands, in order to ensure real-time morphing. A target focus of this new design is to obtain at least 1% in fuel consumption and around 0.5% of CO2 decrease. This meets the principal greening objectives of H2020 and its prospective for the next decade in respect of energy harvesting, pollution reduction and more safe aircraft transport.
Overview of the project's results
The SMS project provided the following major results during the first 18 months:
- Efficient actuation systems for the RS and LS prototypes, able to operate at different time and length scales: high-deformation/slow frequency (order of 1Hz) and low deformation/higher-frequency vibrations (order of 500 Hz). The association of both ensured the so-called “hybrid elctroactive morphing”, which is partly bio-inspired from the flight of large span hunting birds. This kind of morphing, applied in the case of the sRS prototype is proven able to considerably increase the aerodynamic performances: by means of camber control, a lift increase of over 10% is obtained. By associating high-camber and optimal higher frequency vibrations in the range of 200-300 Hz together with slight deformation of the near-trailing edge region along 4-5 cm, an order of more 3% lift increase is achieved. Furthermore, a simultaneous decrease of drag of 4-5% is obtained as well as noise sources reduction of order 8%.
These benefits have been realised thanks to two classes of smart electroactive materials (smart actuators): Shape Memory Alloys (SMA) for the high deformations and piezo-actuators of Macro-Fiber Composite type (MFC) ensuring the higher-frequency vibrations, operating in quite moderate amplitudes: fraction of 1 mm. The implementation of the hybrid morphing is a breakthrough of the SMS project.
- Suitable manipulation of the turbulent vortices around the rear part of the wing and in its wake, in order to break down harmful ones and to enhance beneficial vortices thanks to optimal actuations, able to thinning the shear layers and the wake, providing by feedback drag reduction and to lift increase.
-Clear explanation and analysis of the physical mechanisms optimised by the electroactive morphing leading to the aerodynamic performance increase (lift-to-drag-ratio) of order 5 to 10% according to different flight phases: take-off, landing and cruise, thanks to a strong synergy among the Hi-Fi simulations and the aerodynamic experiments.
- Design of the LS prototype (a two-element A320 type wing with its high-lift flap) in full scale, enabled by high-camber morphing capable to bear and to distribute the right aerodynamic forces in full scale conditions. This design has been realised by means of two kinds of actuators: Electromechanical and SMA. The construction of the LS static prototype has been achieved and the construction of its morphing part in respect of these two kinds of actuators is under final realisation.
- Wind tunnel experimental verification achievements for the sRS and the LS prototype in two wind tunnels of test section 70cm and 2,40 m respectively, corresponding to the take-off configurations
- Achievement of economic electrical power supply systems for the morphing: order of a decade of W for the RS prototype and of 50 KW for the LS one, as well as ability of force bearing of order 1,5 t for the LS prototype. Moreover, the added weight on the wing’s structure is quite light comparing to other more heavy systems based on MEMS or conventional hydromechanical actuators.
-A novel actuation system has been implemented, the hybrid electroactive morphing, acting at different times and length scales in respect of the turbulent vortex structures surrounding the wing. This sytem is able to increase lift, beyond the increase obtained by camber control, by an order of 3% more lift thanks to higher-frequency vibrations and slight deformations of the near-trailing edge region thanks to specific piezoactuators.
-Analysis and explanation of the morphing interaction on the instabilities and turbulence and feedback thanks to optimal manimulation of turbulence able to attenuate the harmful turbulence structures and to enhance beneficial ones providing a significant feedback on the solid structure with considerable increase of the aerodynamic performances.
- Adaptation of the morphing actuations in all the phases of flight: take-off , landing and cruise
- Implementation of a novel system of sensors based on Bragg grating, able to provide simultaneous pressure fluctuation measurements in a multiple points.
-Controller design based to efficient sensing/morphing interaction
-Sensitivity matrix evaluation in respect of camber and higher-frequency vibration actuations thanks to Hi-Fi simulations with advanced CFD in strong synergy with the experiments
-Simultaneous drag reduction by an order of 5% and of aerodynamic noise by an order of 8%
-Design and measurements on morphing prototypes including full-scale high-lift flap
Impact: an intense dissemination/communication activity of the SMS project has been carried out during RP1, described in the Technical report.
A major outcome of the SMS project is that it produces a simultaneous drag decrease and a lift-to-drag increase of 5.12 % thanks to the hybrid morphing.