Numerical Investigation of Aerodynamic Performance of Low Aspect Ratio Wing with Leading Edge Vortex Generators

A sweptback angle can directly regulate a leading-edge vortex on various aerodynamic devices as well as on the wings of biological flyers, but the effect of a sweptback angle has not yet been sufficiently investigated. Here, we thoroughly investigated the effect of the sweptback angle on aerodynamic characteristics of low-aspect-ratio flat plates at a Reynolds number of 2.85 × 104. Direct force/moment measurements and surface oil-flow visualizations were conducted in the wind-tunnel B at the Technical University of Munich. It was found that while the maximum lift at an aspect ratio of 2.03 remains unchanged, two other aspect ratios of 3.13 and 4.50 show a gradual increment in the maximum lift with an increasing sweptback angle. The largest leading-edge vortex contribution was found at the aspect ratio of 3.13, resulting in a superior lift production at a sufficient sweptback angle. This is similar to that of a revolving/flapping wing, where an aspect ratio around three shows a superior lift production. In the oil-flow patterns, it was observed that while the leading-edge vortices at aspect ratios of 2.03 and 3.13 fully covered the surfaces, the vortex at an aspect ratio of 4.50 only covered up the surface approximately three times the chord, similar to that of a revolving/flapping wing. Based on the pattern at the aspect ratio of 4.50, a critical length of the leading-edge vortex of a sweptback plate was measured as ~3.1 times the chord.

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Aerodynamic Performance Improvement of UAV by means of Leading-Edge Vortex Generators

2019 IEEE 5th International Conference Actual Problems of Unmanned Aerial Vehicles Developments (APUAVD) ◽

10.1109/apuavd47061.2019.8943866 ◽

2019 ◽

Author(s):

Artemii Sattarov ◽

Eugene Udartsev ◽

Volodymyr Rozbytskyi ◽

Olexander Zhdanov

Keyword(s):

Performance Improvement ◽

Leading Edge ◽

Aerodynamic Performance ◽

Vortex Generators ◽

Leading Edge Vortex ◽

Edge Vortex

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Interplay of the leading-edge vortex and the tip vortex of a low-aspect-ratio thin wing

Experiments in Fluids ◽

10.1007/s00348-020-03023-4 ◽

2020 ◽

Vol 61 (9) ◽

Author(s):

Lei Dong ◽

Kwing-So Choi ◽

Xuerui Mao

Keyword(s):

Aspect Ratio ◽

Angle Of Attack ◽

Three Dimensional ◽

Separated Flow ◽

Leading Edge ◽

Tip Vortex ◽

Leading Edge Vortex ◽

Low Aspect Ratio ◽

Thin Wing ◽

Edge Vortex

Abstract Three-dimensional vortical structures and their interaction over a low-aspect-ratio thin wing have been studied via particle image velocimetry at the chord Reynolds number of $$10^5$$ 10 5 . The maximum lift of this thin wing is found at an angle of attack of $$42^\circ$$ 42 ∘ . The flow separates at the leading-edge and reattaches to the wing surface, forming a strong leading-edge vortex which plays an important role on the total lift. The results show that the induced velocity of the tip vortex increases with the angle of attack, which helps reattach the separated flow and maintains the leading-edge vortex. Turbulent mixing indicated by the high Reynolds stress can be observed near the leading-edge due to an intense interaction between the leading-edge vortex and the tip vortex; however, the reattachment point of the leading-edge vortex moves upstream closer to the wing tip. Graphic abstract

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Leading-edge vortex burst on a low-aspect-ratio rotating flat plate

Physical Review Fluids ◽

10.1103/physrevfluids.1.044501 ◽

2016 ◽

Vol 1 (4) ◽

Cited By ~ 12

Author(s):

Albert Medina ◽

Anya R. Jones

Keyword(s):

Aspect Ratio ◽

Flat Plate ◽

Leading Edge ◽

Leading Edge Vortex ◽

Low Aspect Ratio ◽

Edge Vortex

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

Journal of The Royal Society Interface ◽

10.1098/rsif.2017.0933 ◽

2018 ◽

Vol 15 (143) ◽

pp. 20170933 ◽

Cited By ~ 12

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.

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