Experimental investigation on the wing-wake interaction at the mid stroke in hovering flight of dragonfly

Lai, Guosong; Shen, Gongxin

doi:10.1007/s11433-012-4907-2

Cited by 19 publications

(12 citation statements)

References 68 publications

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“…The first group reported that the forewing LEV spans the dragonfly body from tip to tip, while the hindwing typically exhibits attached flow (Thomas et al, 2004). However, Lai and Shen (2012) hypothesized that the LEV extending over the body could be caused by the wind tunnel flow and the tilted body alignment of the dragonfly during takeoff (Lai and Shen, 2012).…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic characteristics along the wing span of a dragonflyPantala Flavescens

Hefler

Qiu

Shyy

2018

Journal of Experimental Biology

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We investigated the characteristics of interwing aerodynamic interactions across the span of the high aspect ratio, flexible wings of dragonflies under tethered and free-flying conditions. This revealed that the effects of the interactions on the hindwings vary across four spanwise regions. (i) Close to the wing root, a trailing-edge vortex (TEV) is formed by each stroke, while the formation of a leading-edge vortex (LEV) is limited by the short translational distance of the hindwing and suppressed by the forewing-induced flow. (ii) In the region away from the wing root but not quite up to midspan, the formation of the hindwing LEV is influenced by that of the forewing LEV. This vortex synergy can increase the circulation of the hindwing LEV in the corresponding cross-section by 22% versus that of the hindwing in isolation. (iii) In the region about half-way between the wing root and wing tip there is a transition dominated by downwash from the forewing resulting in flow attached to the hindwing. (iv) A LEV is developed in the remaining, outer region of the wing at the end of a stroke when the hindwing captures the vortex shed by the forewing. The interaction effects depend not only on the wing phasing but also on the flapping offset and flight direction. The aerodynamics of the hindwings vary substantially from the wing root to the wing tip. For a given phasing, this spanwise variation in the aerodynamics can be exploited in the design of artificial wings to achieve greater agility and higher efficiency.

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Section: Introductionmentioning

confidence: 99%

Aerodynamic characteristics along the wing span of a dragonflyPantala Flavescens

Hefler

Qiu

Shyy

2018

Journal of Experimental Biology

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“…[10]. Experiment by Lai and Shen [19] revealed that a wake vortex from the forewing traversed the upper surface of the hindwing became an additional LEV of the hindwing and can partly compensate the hindwing lift loss caused by the downwash from the forewing.…”

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confidence: 99%

Aerodynamic interaction between forewing and hindwing of a hovering dragonfly

Deng

2014

Acta Mech Sin

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The phase change between the forewing and hindwing is a distinct feature that sets dragonfly apart from other insects. In this paper, we investigated the aerodynamic effects of varying forewing-hindwing phase difference with a 60 • inclined stroke plane during hovering flight. Force measurements on a pair of mechanical wing models showed that in-phase flight enhanced the forewing lift by 17% and the hindwing lift was reduced at most phase differences. The total lift of both wings was also reduced at most phase differences and only increased at a phase range around in-phase. The results may explain the commonly observed behavior of the dragonfly where 0 • is employed in acceleration. We further investigated the wing-wing interaction mechanism using the digital particle image velocimetry (PIV) system, and found that the forewing generated a downwash flow which is responsible for the lift reduction on the hindwing. On the other hand, an upwash flow resulted from the leading edge vortex of the hindwing helps to enhance lift on the forewing. The results suggest that the dragonflies alter the phase differences to control timing of the occurrence of flow interactions to achieve certain aerodynamic effects.

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“…Experiments by Lai et al. 32 revealed that a wake vortex generated from the forewing flowing over the upper surface of the hindwing at mid-down stroke causes an additional LEV that partially compensates the hindwing lift loss caused by the downwash from the forewing. Broering et al.…”

Section: Dragonfly Flightsmentioning

confidence: 99%

A review of aerodynamic studies on dragonfly flight

Salami

Ward

Montazer

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part C:

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In the recent decades, the design and development of biomimetic micro air vehicles have gained increased interest by the global scientific and engineering communities. This has given greater motivation to study and understand the aerodynamics involved with winged insects. Dragonflies demonstrate unique and superior flight performance than most of the other insect species and birds. They are capable of sustained gliding flight as well as hovering and able to change direction very rapidly. Pairs of independently controlled forewings and hindwings give them an agile flying ability. This article presents a review of all published journal articles, listed in the Thomson-Reuters Web-of-Science database (1985–2018), that are related to the flight aerodynamics of dragonflies or micro air vehicles that biomimic them. The effects of dragonfly wing motions and interactions (between forewing and hindwing) that are necessary to generate the appropriate aerodynamic forces in different flight modes are described. The associated power requirements of these modes are also addressed. This article aims to provide a valuable reference to the aerodynamic design and control of dragonfly-inspired biomimetic micro air vehicles.

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Experimental investigation on the wing-wake interaction at the mid stroke in hovering flight of dragonfly

Cited by 19 publications

References 68 publications

Aerodynamic characteristics along the wing span of a dragonflyPantala Flavescens

Aerodynamic characteristics along the wing span of a dragonflyPantala Flavescens

Aerodynamic interaction between forewing and hindwing of a hovering dragonfly

A review of aerodynamic studies on dragonfly flight

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