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Kinematic and Aerodynamic Investigation of the Butterfly in Forward Free Flight for the Butterfly-Inspired Flapping Wing Air Vehicle

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Yixin Zhang at Beihang University (BUAA)
Yixin Zhang
Xingjian Wang
Xingjian Wang
Xingjian Wang
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Shao-Ping Wang
Shao-Ping Wang
Wenhao Huang
Wenhao Huang
Wenhao Huang
  • This person is not on ResearchGate, or hasn't claimed this research yet.
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Abstract and Figures

To ensure the stability of flight, the butterfly needs to flap its wings and simultaneously move its main body to achieve all kinds of flying motion, such as taking off, hovering, or reverse flight. The high-speed camera is used to record the swing of the abdomen, the movement of the wings, and the pitch angle of the body for butterflies during their free flight; the comprehensive biokinetic observations show that the butterfly’s wings and body are coupled in various flight states. The swing of the abdomen and the flap of the fore wing affect the pitch motion significantly. For theoretical analysis of the butterfly flight, a three-dimensional multi-rigid butterfly model based on real butterfly dimension is established, and the aerodynamic of the butterfly flight is simulated and analyzed via computational fluid dynamics methods to obtain an optimal kinematic model of butterfly forward flight. Moreover, the formation and development of three-dimensional vortex structures in the forward flight are also presented. The detailed structures of vortices and their dynamic behavior show that the wing’s flap and the abdominal swing play a key role in reorienting and correcting the “clap and peel” mechanism, and the force generation mechanisms are evaluated. The research indicates that longitudinal flight performance is mainly related to the kinematic parameters of the wing and body, and it can lead to the development of butterfly-inspired flapping wing air vehicles.
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Article
Full-text available
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Preprint
Full-text available
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Article
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Article
Full-text available
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Article
Full-text available
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Article
Full-text available
  • May 2016
Wing-motion of hovering small fly Liriomyza sativae was measured using high-speed video and flows of the wings calculated numerically. The fly used high wingbeat frequency (≈265 Hz) and large stroke amplitude (≈182°); therefore, even if its wing-length (R) was small (R ≈ 1.4 mm), the mean velocity of wing reached ≈1.5 m/s, the same as that of an average-size insect (R ≈ 3 mm). But the Reynolds number (Re) of wing was still low (≈40), owing to the small wing-size. In increasing the stroke amplitude, the outer parts of the wings had a "clap and fling" motion. The mean-lift coefficient was high, ≈1.85, several times larger than that of a cruising airplane. The partial "clap and fling" motion increased the lift by ≈7%, compared with the case of no aerodynamic interaction between the wings. The fly mainly used the delayed stall mechanism to generate the high-lift. The lift-to-drag ratio is only 0.7 (for larger insects, Re being about 100 or higher, the ratio is 1-1.2); that is, although the small fly can produce enough lift to support its weight, it needs to overcome a larger drag to do so.
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Control of Pitch Attitude by Abdomen During Forward Flight of Two-Dimensional Butterfly
Article
  • Jun 2018
The objective of this paper is to understand roles of abdominal motion in the pitch stability of flapping flights of butterflies numerically, and a two-dimensional butterfly model has thoracic pitch instability in the periodically flapping flight. Because the obtained uncontrolled flight is unstable, the hierarchical sliding-mode control is used to design the control input for thorax–abdomen joint torque. It is found in the controlled flight that the abdominal motion is sufficient to counteract the thoracic pitch instability and can maintain flapping flights with short recovery time to artificial thoracic torque perturbations. On the other hand, it is also found that the long-term pitch stabilization is not possible only by the abdominal control for all flapping trajectories. However, with the introduction of a wing lead–lag control, the long-term pitch stabilization is obtained. Hence, these observations indicate that the abdomen is used for a short-term control and the wing for a long-term control in stabilizing the pitch of the butterfly’s flight.
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Generic Analytical Thrust-Force Model for Flapping Wings
Article
  • Oct 2017
The purpose of this paper is to propose a generic analytical flapping-wing cycle-average thrust-force estimation method by implementing elongated body theory into actuator disk theory. Compared with previous a flapping-wing analysis based on actuator disk theory, the proposed method relates wing geometry and kinematics directly to induced velocity, and the periodical pressure pulsation correction factor measurement for every different flapping-wing design is no longer necessary. The proposed method is much simpler than unsteady aerodynamics or computational implementations, and thus the complex multiparameter optimization can be avoided at the early design stage of flapping-wing vehicles. Theoretical deviation of the proposed thrust model is evaluated by a numerical simulation method, and a correction term is proposed. The corrected method is then validated by wind-tunnel experiments on an 850-cm-wing-span active-twisting flapping-wing model and experimental data from previous studies that were over large parameter ranges. The results suggest that the proposed method is valid for the flapping-wing cycle-average thrust estimation over a large range of variables. Theoretical deductions about the effects of dominant factors of flapping-wing propulsion behavior and application of the present method in both passive- and active-twisting flapping-wing designs are also discussed.
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Importance of body rotation during the flight of a butterfly
Article
  • Mar 2016
  • PRE
In nature the body motion of a butterfly is clearly observed to involve periodic rotation and varied flight modes. The maneuvers of a butterfly in flight are unique. Based on the flight motion of butterflies (Kallima inachus) recorded in free flight, a numerical model of a butterfly is created to study how its flight relates to body pose; the body motion in a simulation is prescribed and tested with varied initial body angle and rotational amplitude. A butterfly rotates its body to control the direction of the vortex rings generated during flapping flight; the flight modes are found to be closely related to the body motion of a butterfly. When the initial body angle increases, the forward displacement decreases, but the upward displacement increases within a stroke. With increased rotational amplitudes, the jet flows generated by a butterfly eject more downward and further enhance the generation of upward force, according to which a butterfly executes a vertical jump at the end of the downstroke. During this jumping stage, the air relative to the butterfly is moving downward; the butterfly pitches up its body to be parallel to the flow and to decrease the projected area so as to avoid further downward force generated. Our results indicate the importance of the body motion of a butterfly in flight. The inspiration of flight controlled with body motion from the flight of a butterfly might yield an alternative way to control future flight vehicles.
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