Vortices behavior depending on the aspect ratio of an insect-like flapping wing in hover

2015 ◽  
Vol 56 (9) ◽  
Author(s):  
Jong-Seob Han ◽  
Jo Won Chang ◽  
Hwan-Kee Cho
Keyword(s):  
Aspect Ratio ◽  
Flapping Wing

Induced Strain Actuation for Solid-State Ornithopters: An Aeroelastic Study

2018 ◽  
Author(s):  
Francis Hauris ◽  
Onur Bilgen
Keyword(s):  
Reynolds Number ◽  
Solid State ◽  
Aspect Ratio ◽  
Interaction Model ◽  
Flapping Wing ◽  
Flapping Wings ◽  
Structural Behavior ◽  
Structure Interaction ◽  
Dynamic Motion ◽  
Lift And Drag

This paper investigates the dynamic aeroelastic behavior of strain actuated flapping wings with various geometries and boundary conditions. A fluid-structure interaction model of a plate-like flapping wing is developed. Assuming a chord Reynolds number of 100,000, the wing is harmonically actuated while varying parameters such as aspect ratio and wing root clamped percentage. Characteristic metrics for the dynamic motion, natural frequency, lift and drag are developed. These results are compared with purely structural behavior to understand the aeroelastic effects.

Wing-Wake Interaction of Insect-Like Flapping Wing in Hover: Effect of Aspect Ratio and Kinematics at Re~104

2019 ◽  
Author(s):  
Reynolds Addo-Akoto ◽  
Jong-Seob Han ◽  
Jae-Hung Han
Keyword(s):  
Aspect Ratio ◽  
Time Course ◽  
Aerodynamic Force ◽  
Flapping Wing ◽  
Windward Side ◽  
Water Tank ◽  
Image Velocimetry ◽  
Wake Interaction ◽  
Entire Flow ◽  
Accelerated Flow

Abstract In this paper, the effect of wing aspect ratio and kinematics on wing-wake interaction at Re∼104, which matched the flight regime of flapping-wing micro air vehicle (FWMAV), was investigated. The dynamically scaled-up robotic model submerged in a water tank environment revealed that the wing-wake interaction augmented lift across a decrease in both aspect ratio and wing pitching duration. At such high Re, a time-course digital particle image velocimetry (DPIV) measurement showed the entire flow was strongly dominated by trailing-edge vortices (TEV). A pair of counter-rotating TEV was found to induce a jetlike flow towards the windward side of the wing at stroke reversal. The transfer of momentum from the accelerated flow to the wing caused the enhanced lift. The size of the pair vortex decreased for an increase in both aspect ratio and wing pitching duration. The size of the TEV pair was the key feature found to generate the observed aerodynamic force characteristics.

scholarly journals The effect of aspect ratio on the leading-edge vortex over an insect-like flapping wing

2015 ◽  
Vol 10 (5) ◽  
pp. 056020 ◽  
Author(s):  
Nathan Phillips ◽  
Kevin Knowles ◽  
Richard J Bomphrey
Keyword(s):  
Aspect Ratio ◽  
Leading Edge ◽  
Flapping Wing ◽  
Leading Edge Vortex ◽  
Edge Vortex

Influence of aspect ratio on wing–wake interaction for flapping wing in hover

2019 ◽  
Vol 60 (11) ◽  
Author(s):  
Reynolds Addo-Akoto ◽  
Jong-Seob Han ◽  
Jae-Hung Han
Keyword(s):  
Aspect Ratio ◽  
Flapping Wing ◽  
Wake Interaction

scholarly journals Leading-Edge Vortex Characteristics of Low-Aspect-Ratio Sweptback Plates at Low Reynolds Number

2021 ◽  
Vol 11 (6) ◽  
pp. 2450
Author(s):  
Jong-Seob Han ◽  
Christian Breitsamter
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Leading Edge ◽  
Flapping Wing ◽  
Flat Plates ◽  
Leading Edge Vortex ◽  
Low Aspect Ratio ◽  
Aspect Ratios ◽  
Oil Flow ◽  
Edge Vortex

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.

Bio-inspired design of flapping-wing micro air vehicles

2005 ◽  
Vol 109 (1098) ◽  
pp. 385-393 ◽  
Author(s):  
K. D. Jones ◽  
C. J. Bradshaw ◽  
J. Papadopoulos ◽  
M. F. Platzer
Keyword(s):  
Aspect Ratio ◽  
Figure Of Merit ◽  
Ground Effect ◽  
Micro Air Vehicles ◽  
Flapping Wing ◽  
Flapping Wings ◽  
Rechargeable Battery ◽  
Flight Testing ◽  
Low Aspect Ratio ◽  
Air Vehicles

AbstractIn this paper the development and flight testing of flapping-wing propelled, radio-controlled micro air vehicles are described. The unconventional vehicles consist of a low aspect ratio fixed-wing with a trailing pair of higher aspect ratio flapping wings which flap in counterphase. The symmetric flapping-wing pair provides a mechanically and aerodynamically balanced platform, increases efficiency by emulating flight in ground effect, and suppresses stall over the main wing by entraining flow. The models weigh as little as 11g, with a 23cm span and 18cm length and will fly for about 20 minutes on a rechargeable battery. Stable flight at speeds between 2 and 5ms–1has been demonstrated, and the models are essentially stall-proof while under power. The static-thrust figure of merit for the device is 60% higher than propellers with a similar scale and disk loading.

Effects of aspect ratio on flapping wing aerodynamics in animal flight

2014 ◽  
Vol 30 (6) ◽  
pp. 776-786 ◽  
Author(s):  
Jun-Jiang Fu ◽  
Csaba Hefler ◽  
Hui-He Qiu ◽  
Wei Shyy
Keyword(s):  
Aspect Ratio ◽  
Flapping Wing ◽  
Animal Flight ◽  
Wing Aerodynamics
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