An experimental parametric study on planar sheared wings tip devices for low-to-moderate aspect ratio wings

Purpose The purpose of this study is to investigate the aerodynamic characteristics of a low-to-moderate-aspect-ratio, tapered, untwisted, unswept wing, equipped of sheared wing tips. Design/methodology/approach In this work, wind tunnel tests were made to study the influence in aerodynamic characteristics over a typical low-to-moderate-aspect-ratio wing of a general aviation aircraft, equipped with sheared – swept and tapered planar – wing tips. An experimental parametric study of different wing tips was tested. Variations in its leading and trailing edge sweep angle as well as variations in wing tip taper ratio were considered. Sheared wing tips modify the flow pattern in the outboard region of the wing producing a vortex flow at the wing tip leading edge, enhancing lift at high angles of attack. Findings The induced drag is responsible for nearly 50% of aircraft total drag and can be reduced through modifications to the wing tip. Some wing tip models present complex geometries and many of them present benefits in particular flight conditions. Results have demonstrated that sweeping the wing tip leading edge between 60 and 65 degrees offers an increment in wing aerodynamic efficiency, especially at high lift conditions. However, results have demonstrated that moderate wing tip taper ratio (0.50) has better aerodynamic benefits than highly tapered wing tips (from 0.25 to 0.15), even with little less wing tip leading edge sweep angle (from 57 to 62 degrees). The moderate wing tip taper ratio (0.50) offers more wing area and wing span than the wings with highly tapered wing tips, for the same aspect ratio wing. Originality/value Although many studies have been reported on the aerodynamics of wing tips, most of them presented complex non-planar geometries and were developed for cruise flight in high subsonic regime (low lift coefficient). In this work, an exploration and parametric study through wind tunnel tests were made, to evaluate the influence in aerodynamic characteristics of a low-to-moderate-aspect-ratio, tapered, untwisted, unswept wing, equipped of sheared wing tips (wing tips highly swept and tapered).

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Modification of the NACA 632-415 Leading Edge for Better Aerodynamic Performance

Journal of Solar Energy Engineering ◽

10.1115/1.1506324 ◽

2002 ◽

Vol 124 (4) ◽

pp. 327-334 ◽

Cited By ~ 6

Author(s):

Christian Bak ◽

Peter Fuglsang

Keyword(s):

Wind Tunnel ◽

Wind Turbines ◽

Power Level ◽

Leading Edge ◽

Aerodynamic Characteristics ◽

Dynamic Stall ◽

Wind Tunnel Tests ◽

Damping Characteristics ◽

Edge Roughness ◽

Drag Ratio

Double stall causes more than one power level when stall-regulated wind turbines operate in stall. This involves significant uncertainty on power production and loads. To avoid double stall, a new leading edge was designed for the NACA 632-415 airfoil, an airfoil that is often used in the tip region of wind turbines. A numerical optimization tool incorporating XFOIL was used with a special formulation for the airfoil leading edge shape. The EllipSys2D CFD code was used to analyze the modified airfoil. In theory and in wind tunnel tests, the modified airfoil showed smooth and stable stall characteristics with no tendency to double stall. Also, both theory and wind tunnel tests showed that the overall aerodynamic characteristics were similar to NACA 632-415 except for an increase in the lift-drag ratio below maximum lift and an increase in maximum lift. The wind tunnel tests showed that dynamic stall and aerodynamic damping characteristics for the modified airfoil and the NACA 632-415 airfoil were the same. The modified airfoil with leading edge roughness in general had better characteristics compared with the NACA 632-415 airfoil.

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Wind tunnel tests of the inverted joined wing and a comparison with CFD results

Aircraft Engineering and Aerospace Technology ◽

10.1108/aeat-11-2016-0195 ◽

2018 ◽

Vol 90 (4) ◽

pp. 586-601

Author(s):

Cezary Galinski ◽

Grzegorz Krysztofiak ◽

Marek Miller ◽

Pawel Ruchala ◽

Marek Kalski ◽

...

Keyword(s):

Wind Tunnel ◽

Aerodynamic Characteristics ◽

Control Surface ◽

Dual Use ◽

Wind Tunnel Tests ◽

Content Type ◽

Flying Qualities ◽

Computational Fluid Dynamics Cfd ◽

Joined Wing ◽

Surface Deflections

Purpose The purpose of this paper is to present the methodology and approach adapted to conduct a wind tunnel experiment on the inverted joined-wing airplane flying model together with the results obtained. Design/methodology/approach General assumptions underlying the dual-use model design are presented in this paper. The model was supposed to be used for both wind tunnel tests and flight tests that significantly drive its size and internal structure. Wind tunnel tests results compared with the outcome of computational fluid dynamics (CFD) were used to assess airplane flying qualities before the maiden flight was performed. Findings Extensive data about the aerodynamic characteristics of the airplane were collected. Clean configurations in symmetric and asymmetric cases and also configurations with various control surface deflections were tested. Practical implications The data obtained experimentally made it possible to predict the performance and stability properties of the unconventional airplane and to draw conclusions on improvements in further designs of this configuration. Originality/value The airplane described in this paper differs from frequently analyzed joined-wing configurations, as it boasts a front lifting surface attached at the top of the fuselage, whereas the aft one is attached at the bottom. The testing technique involving the application of a dual-use model is also innovative.

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Wind Tunnel Test of A R.A.F.28 Aerofoil with Thurston Rotors

Journal of the Royal Aeronautical Society ◽

10.1017/s036839310011017x ◽

1934 ◽

Vol 38 (278) ◽

pp. 141-161

Author(s):

A. S. Hartshorn ◽

C. Callen

Keyword(s):

Wind Tunnel ◽

Wind Tunnel Test ◽

Leading Edge ◽

Lateral Stability ◽

Primary Object ◽

Wing Tips ◽

Wing Tip

The suggestion has been put forward by Dr. A. P. Thurston that the characteristics of a wing can be considerably improved by adding self-starting rotors at or near the wing tips. It is claimed that by placing these on each wing near the leading edge improvements analogous to those of a slotted wing tip can be obtained together with slow landing characteristics. Previous experiments (1) have shown that rotors can give about the same degree of lateral stability as tip slots. The primary object of these experiments was to test the second assertion, and the criterion by which this should be judged was that the gliding angle should be as steep as possible for a given rate of descent.

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Simulation of a passenger aircraft flight with the wing tip cut

Aircraft Engineering and Aerospace Technology ◽

10.1108/aeat-12-2020-0294 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Zdobyslaw Jan Goraj ◽

Mariusz Kowalski ◽

Łukasz Kiszkowiak ◽

Aleksander Olejnik

Keyword(s):

Wind Tunnel ◽

Flow Separation ◽

Pitch Angle ◽

Equations Of Motion ◽

Aerodynamic Characteristics ◽

Final Phase ◽

Total Flow ◽

Content Type ◽

Passenger Aircraft ◽

Wing Tip

Purpose The purpose of this paper is to present the result of simulations that were performed to assess the uncontrolled motion of the passenger aircraft following its wing tip was suddenly cut. Such a simulation can help to understand the tendencies of aircraft behaviour after wing tip cut, assess how fast this phenomenon is going on and estimate the values of angles of attack, sideslip and pitch angle basing on given aerodynamic characteristics. Also, answer the question if pilot can counteract high deviations from flight path initially planned during the final phase of approach to landing. Design/methodology/approach Simulation is based on the full non-linear equations of motion derived from generalised equations of change of momentum and moment of momentum of rigid body. Dynamic equations of motion in the so-called normal mode are solved in the so-called stability frame of reference. Findings It was found that asymmetric rolling moment must be compensated by essential increase of pitching moment. Moreover, it appeared that aircraft goes into high angles of attack and high pitch angle and, therefore, for reliable simulation, the available aerodynamic characteristics must include angles of attack till 90 degrees when total flow separation occurs. Practical implications For accurate simulation, it is strongly recommended to perform to perform first the wind tunnel testing in the range of +20o ÷ 120o and use it in flight simulation. Originality/value The presented methodology is an original for numerical simulation of flight trajectory during the final phase of approach to landing in a hazardous state of flight. For reliable simulation, the available aerodynamic characteristics must include angles of attack till 90 degrees when total flow separation occurs, whereas usually maximum angles of attack used in wind tunnel experiments for passenger aircraft are not higher than 25 degrees. The influence of limited range of experimental data on results of simulation is another value which can be adopted in the future investigations of hazardous states of flight.

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Preliminary investigation of use of flexible folding wing tips for static and dynamic load alleviation

The Aeronautical Journal ◽

10.1017/aer.2016.108 ◽

2016 ◽

Vol 121 (1235) ◽

pp. 73-94 ◽

Cited By ~ 19

Author(s):

A. Castrichini ◽

V. Hodigere Siddaramaiah ◽

D.E. Calderon ◽

J.E. Cooper ◽

T. Wilson ◽

...

Keyword(s):

Aspect Ratio ◽

Preliminary Investigation ◽

Aircraft Design ◽

Dynamic Loads ◽

Induced Drag ◽

Aeroelastic Model ◽

Static And Dynamic Loads ◽

Folding Wing ◽

Wing Tips ◽

Wing Tip

ABSTRACTA recent consideration in aircraft design is the use of folding wing-tips with the aim of enabling higher aspect ratio aircraft with less induced drag while also meeting airport gate limitations. This study investigates the effect of exploiting folding wing-tips in flight as a device to reduce both static and dynamic loads. A representative civil jet aircraft aeroelastic model was used to explore the effect of introducing a wing-tip device, connected to the wings with an elastic hinge, on the load behaviour. For the dynamic cases, vertical discrete gusts and continuous turbulence were considered. The effects of hinge orientation, stiffness, damping and wing-tip weight on the static and dynamic response were investigated. It was found that significant reductions in both the static and dynamic loads were possible. For the case considered, a 25% increase in span using folding wing-tips resulted in almost no increase in loads.

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Leading Edge and Wing Tip Flow Control on Low Aspect Ratio Wings

40th Fluid Dynamics Conference and Exhibit ◽

10.2514/6.2010-4865 ◽

2010 ◽

Cited By ~ 7

Author(s):

Stefan Vey ◽

David Greenblatt ◽

Christian Nayeri ◽

Christian Paschereit

Keyword(s):

Aspect Ratio ◽

Flow Control ◽

Leading Edge ◽

Low Aspect Ratio ◽

Wing Tip ◽

Low Aspect Ratio Wings

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Experimental analysis of fluid-structure interaction in flexible wings at low Reynolds number flows

Aircraft Engineering and Aerospace Technology ◽

10.1108/aeat-04-2021-0120 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Mustafa Serdar Genç ◽

Hacımurat Demir ◽

Mustafa Özden ◽

Tuna Murat Bodur

Keyword(s):

Reynolds Number ◽

Aspect Ratio ◽

Fluid Structure Interaction ◽

Leading Edge ◽

Flexible Wings ◽

Flexible Membrane ◽

Fluid Structure ◽

Content Type ◽

Structure Interaction ◽

Membrane Deformations

Purpose The purpose of this exhaustive experimental study is to investigate the fluid-structure interaction in the flexible membrane wings over a range of angles of attack for various Reynolds numbers. Design/methodology/approach In this paper, an experimental study on fluid-structure interaction of flexible membrane wings was presented at Reynolds numbers of 2.5 × 104, 5 × 104 and 7.5 × 104. In the experimental studies, flow visualization, velocity and deformation measurements for flexible membrane wings were performed by the smoke-wire technique, multichannel constant temperature anemometer and digital image correlation system, respectively. All experimental results were combined and fluid-structure interaction was discussed. Findings In the flexible wings with the higher aspect ratio, higher vibration modes were noticed because the leading-edge separation was dominant at lower angles of attack. As both Reynolds number and the aspect ratio increased, the maximum membrane deformations increased and the vibrations became visible, secondary vibration modes were observed with growing the leading-edge vortices at moderate angles of attack. Moreover, in the graphs of the spectral analysis of the membrane displacement and the velocity; the dominant frequencies coincided because of the interaction of the flow over the wings and the membrane deformations. Originality/value Unlike available literature, obtained results were presented comparatively using the sketches of the smoke-wire photographs with deformation measurement or turbulence statistics from the velocity measurements. In this study, fluid-structure interaction and leading-edge vortices of membrane wings were investigated in detail with increasing both Reynolds number and the aspect ratio.

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