scholarly journals Experimental Study of Flexible Skin Designs Between a Moving Wing Segment and a Fixed Wing Part on a Full Scale Demonstrator

2020 ◽  
Author(s):  
Martin Radestock ◽  
Johannes Riemenschneider ◽  
Alexander Falken ◽  
Johannes Achleitner
Keyword(s):  
Control Systems ◽  
Optical Measurement ◽  
Leading Edge ◽  
Full Scale ◽  
Smooth Transition ◽  
Plane Shear ◽  
High Lift ◽  
Local Skin ◽  
Flexible Skin ◽  
Triangular Design

Abstract Commercial aircraft today require efficient high-lift and control systems on the wings to reduce the drag in flight or decrease the take-off and landing speeds. Morphing mechanisms are one approach for improved high-lift systems. In most cases the objective function is an increased lift to drag ratio or the noise reduction. On closer examination control systems as well as morphing mechanisms are located in a certain wing segment. The transition between a moving wing part and the fixed wing is a step, which creates additional vortices. This segments the wing in span-wise direction and reduces the efficiency. A flexible skin between a moving and a fixed wing parts smooths the contour and minimize the efficiency reduction of the wing. A full scale demonstrator of a wing segment was manufactured with two flexible skin designs. The first subcomponent connects a morphing leading edge with a rib of the wing over a span of one meter. The skin is a material mix of ethylene-propylene-diene monomer (EPDM) rubber and fiberglass-reinforced plastic. The rubber is the basis of the skin and the glass-fiber is added as local skin stiffeners in the form of strips in chord-wise direction. The second subcomponent blends the aileron with a rib of the wing in a triangular design. The connection of three different hinges realizes a morphing triangle, which is loaded in an in-plane shear only state of stress in each aileron position. The core of the triangle is a 3D printed structure, which is free in shear. The covering skin is a combination of EPDM with carbon fibers oriented in +/−30° direction to obtain shear compliance and to resist the loads on the triangle. The deformation of each concept is identified at the demonstrator. Therefore, an optical measurement system scans the surface in the initial and deflected state. The required deformation precision of the concepts differs due to their design. The contour at the leading edge requires a certain shape over the span. The analysis of the skin buckling is one requirement at the transition triangle during the aileron motion. The experimental results show a smooth transition contour at the leading edge and no buckling effects at the triangle. The results can be used for the validation of simulation models. Furthermore, both skin concepts cover the gap between a moving wing segment and a fixed wing part. The elimination of steps in span-wise direction can improve the aero-acoustic behavior along the wing for future aircraft.

scholarly journals Comparison of Constrained Parameterisation Strategies for Aerodynamic Optimisation of Morphing Leading Edge Airfoil

Aerospace ◽  
2019 ◽  
Vol 6 (3) ◽  
pp. 31 ◽  
Author(s):  
Andrea Magrini ◽  
Ernesto Benini ◽  
Rita Ponza ◽  
Chen Wang ◽  
Hamed Khodaparast ◽  
...  
Keyword(s):  
Lift Coefficient ◽  
Pareto Frontier ◽  
Leading Edge ◽  
Geometric Constraints ◽  
Shape Modification ◽  
High Lift ◽  
Morphing Aircraft ◽  
Flexible Skin ◽  
Bending Strain ◽  
Open Issues

In the context of ambitious targets for reducing environmental impact in the aviation sector, dictated by international institutions, morphing aircraft are expected to have potential for achieving the required efficiency increases. However, there are still open issues related to the design and implementation of deformable structures. In this paper, we compare three constrained parameterisation strategies for the aerodynamic design of a morphing leading edge, representing a potential substitute for traditional high-lift systems. In order to facilitate the structural design and promote the feasibility of solutions, we solve a multi-objective optimisation problem, including constraints on axial and bending strain introduced by morphing. A parameterisation method, inherently producing constant arc length curves, is employed in three variants, representing different morphing strategies which provide an increasing level of deformability, by allowing the lower edge of the flexible skin to slide and the gap formed with the fixed spar to be closed by a hatch. The results for the optimisation of a baseline airfoil show that the geometric constraints are effectively handled in the optimisation and the solutions are smooth, with a continuous variation along the Pareto frontier. The larger shape modification allowed by more flexible parameterisation variants enables an increase of the maximum lift coefficient up to 8.35%, and efficiency at 70% of stall incidence up to 4.26%.

scholarly journals Analysis and Design of a Leading Edge with Morphing Capabilities for the Wing of a Regional Aircraft—Gapless Chord- and Camber-Increase for High-Lift Performance

2021 ◽  
Vol 11 (6) ◽  
pp. 2752
Author(s):  
Conchin Contell Asins ◽  
Volker Landersheim ◽  
Dominik Laveuve ◽  
Seiji Adachi ◽  
Michael May ◽  
...  
Keyword(s):  
Leading Edge ◽  
Bird Strike ◽  
High Lift ◽  
Analysis And Design ◽  
Actuation System ◽  
Aerodynamic Properties ◽  
Reinforced Plastic ◽  
Stall Angle ◽  
Carbon Fibre Reinforced Plastic ◽  
Electromechanical Actuation

In order to contribute to achieving noise and emission reduction goals, Fraunhofer and Airbus deal with the development of a morphing leading edge (MLE) as a high lift device for aircraft. Within the European research program “Clean Sky 2”, a morphing leading edge with gapless chord- and camber-increase for high-lift performance was developed. The MLE is able to morph into two different aerofoils—one for cruise and one for take-off/landing, the latter increasing lift and stall angle over the former. The shape flexibility is realised by a carbon fibre reinforced plastic (CFRP) skin optimised for bending and a sliding contact at the bottom. The material is selected in terms of type, thickness, and lay-up including ply-wise fibre orientation based on numerical simulation and material tests. The MLE is driven by an internal electromechanical actuation system. Load introduction into the skin is realised by span-wise stringers, which require specific stiffness and thermal expansion properties for this task. To avoid the penetration of a bird into the front spar of the wing in case of bird strike, a bird strike protection structure is proposed and analysed. In this paper, the designed MLE including aerodynamic properties, composite skin structure, actuation system, and bird strike behaviour is described and analysed.

scholarly journals MODELING OF DISTURBANCES IN STUDY OF CONTROL SYSTEMS

2020 ◽  
Vol 2020 (4) ◽  
pp. 70-79
Author(s):  
Mikhail Vasilevich Lyakhovets ◽  
Georgiy Valentinovich Makarov ◽  
Alexandr Sergeevich Salamatin
Keyword(s):  
Control Systems ◽  
Generating Functions ◽  
Special Functions ◽  
Computer Training ◽  
Full Scale ◽  
Analytical Models ◽  
Scale Model ◽  
Data Series ◽  
Dynamic Databases ◽  
Natural Data

The article is devoted to questions of synthesis of full-scale - model realizations of data series on the basis of natural data for modeling of controllable and uncontrollable influences at research of operating and projected control systems, and also in training systems of computer training. The possibility of formation of model effects on the basis of joint use of multivariate dynamic databases and natural data simulator is shown. Dynamic databases store information that characterizes the typical representative situations of systems in the form of special functions - generating functions. Multiple variability of dynamic databases is determined by the type of the selected generating function, the methods of obtaining parameters (coefficients) of this function, as well as the selected accuracy of approximation. The situation models recovered by generating functions are used as basic components (trends) in the formation of the resulting full-scale - model implementations and are input into the natural data simulator. The data simulator allows for each variant of initial natural data to form an implementation of the perturbation signal with given statistical properties on a given simulation interval limited by the initial natural implementation. This is achieved with the help of a two-circuit structure, where the first circuit is responsible for evaluation and cor-rection of initial properties of the natural signal, and the second - for iterative correction of deviations of properties of the final implementation from the specified ones. The resulting realizations reflect the properties of their full-scale components, which are difficult to describe by analytical models, and are supplemented by model values, allowing in increments to correct the properties to the specified ones. The given approach allows to form set of variants of course of processes on the basis of one situation with different set degree of uncertainty and conditions of functioning.

scholarly journals On the lift-optimal aspect ratio of a revolving wing at low Reynolds number

2018 ◽  
Vol 15 (143) ◽  
pp. 20170933 ◽  
Author(s):  
T. Jardin ◽  
T. Colonius
Keyword(s):  
Aspect Ratio ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Rossby Number ◽  
Subsequent Work ◽  
High Lift ◽  
Low Aspect Ratio ◽  
Axis Of Rotation ◽  
Edge Vortex ◽  
Convergent Solution

Lentink & Dickinson (2009 J. Exp. Biol. 212 , 2705–2719. ( doi:10.1242/jeb.022269 )) showed that rotational acceleration stabilized the leading-edge vortex on revolving, low aspect ratio (AR) wings and hypothesized that a Rossby number of around 3, which is achieved during each half-stroke for a variety of hovering insects, seeds and birds, represents a convergent high-lift solution across a range of scales in nature. Subsequent work has verified that, in particular, the Coriolis acceleration plays a key role in LEV stabilization. Implicit in these results is that there exists an optimal AR for wings revolving about their root, because it is otherwise unclear why, apart from possible morphological reasons, the convergent solution would not occur for an even lower Rossby number. We perform direct numerical simulations of the flow past revolving wings where we vary the AR and Rossby numbers independently by displacing the wing root from the axis of rotation. We show that the optimal lift coefficient represents a compromise between competing trends with competing time scales where the coefficient of lift increases monotonically with AR, holding Rossby number constant, but decreases monotonically with Rossby number, when holding AR constant. For wings revolving about their root, this favours wings of AR between 3 and 4.

The Dassault Mirage G

1969 ◽  
Vol 73 (708) ◽  
pp. 1027-1028
Author(s):  
Henri Deplante
Keyword(s):  
Leading Edge ◽  
Variable Geometry ◽  
Relative Thickness ◽  
Trailing Edge ◽  
High Lift ◽  
Profound Knowledge ◽  
Subsonic Speed ◽  
Trailing Edge Flaps ◽  
Leading Edge Slats

The interest of wings with variable sweepback springs directly from pure commonsense and appeals to no profound knowledge of aerodynamics for its justification. To realise the advantage of variable geometry, it is enough to know that only a wing of small relative thickness is capable of good performance at supersonic speeds and that by increasing the sweepback from 20° to 70° the thickness of a wing is divided by about 2. In the advanced position, the wing offers its full span to the airstream and with high-lift devices in action (leading-edge slats and trailing-edge flaps combined), the aeroplane can develop the considerable lift necessary for take-off and landing as well as for break-through and for slow approach. Wings still advanced but slats, flaps and undercarriage retracted, the aeroplane is in excellent maximum fineness condition for protracted cruising at subsonic speed or for a long wait. As soon as transonic (Mach No of more than 0-8) or supersonic speeds are in question, the wings are progressively folded back.

High-Lift Simulations of Slotted, Natural-Laminar-Flow Airfoils with Drooped Leading Edge

2020 ◽  
Author(s):  
Hector D. Ortiz-Melendez ◽  
Ethan Long ◽  
George Toth ◽  
Kathryn Keely ◽  
James G. Coder
Keyword(s):  
Laminar Flow ◽  
Leading Edge ◽  
High Lift ◽  
Natural Laminar Flow

Roughness Sensitivity Considerations for Thick Rotor Blade Airfoils

2003 ◽  
Vol 125 (4) ◽  
pp. 468-478 ◽  
Author(s):  
R. P. J. O. M. van Rooij ◽  
W. A. Timmer
Keyword(s):  
Turbine Blades ◽  
Leading Edge ◽  
Lower Surface ◽  
Vortex Generators ◽  
Wind Turbine Blades ◽  
High Lift ◽  
Edge Roughness ◽  
Proper Design ◽  
Drag Ratio ◽  
Lift To Drag Ratio

In modern wind turbine blades, airfoils of more than 25% thickness can be found at mid-span and inboard locations. At mid-span, aerodynamic requirements dominate, demanding a high lift-to-drag ratio, moderate to high lift and low roughness sensitivity. Towards the root, structural requirements become more important. In this paper, the performance for the airfoil series DU FFA, S8xx, AH, Risø and NACA are reviewed. For the 25% and 30% thick airfoils, the best performing airfoils can be recognized by a restricted upper-surface thickness and an S-shaped lower surface for aft-loading. Differences in performance of the DU 91-W2-250 (25%), S814 (24%) and Risø-A1-24 (24%) airfoils are small. For a 30% thickness, the DU 97-W-300 meets the requirements best. Reduction of roughness sensitivity can be achieved both by proper design and by application of vortex generators on the upper surface of the airfoil. Maximum lift and lift-to-drag ratio are, in general, enhanced for the rough configuration when vortex generators are used. At inboard locations, 2-D wind tunnel tests do not represent the performance characteristics well because the influence of rotation is not included. The RFOIL code is believed to be capable of approximating the rotational effect. Results from this code indicate that rotational effects dramatically reduce roughness sensitivity effects at inboard locations. In particular, the change in lift characteristics in the case of leading edge roughness for the 35% and 40% thick DU airfoils, DU 00-W-350 and DU 00-W-401, respectively, is remarkable. As a result of the strong reduction of roughness sensitivity, the design for inboard airfoils can primarily focus on high lift and structural demands.

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