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Aerodynamic Effects of Corrugation in Flapping Insect Wings in forward flight

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Journal of Bionic Engineering 2011年第2期8卷 140-150页

作者： Xueguang Meng Mao Sun Ministry-of-Education Key Laboratory of Fluid Mechanics Beijing University of Aeronautics & Astronautics Beijing 100083 P. R. China

We have examined the aerodynamic effects of corrugation in model wings that closely mimic the wing movements of a forward flight bumblebee using the method of computational fluid dynamics. Various corrugated wing models were tested （care was taken to ensure that the corrugation introduced zero camber）. Advance ratio ranging from 0 to 0.57 was considered. The results shown that at all flight speeds considered, the time courses of aerodynamic force of the corrugated wing are very close to those of the flat-plate wing. The cornlgation decreases aerodynamic force slightly. The changes in the mean location of center of pressure in the spanwise and chordwise directions resulting from the corrugation are no more than 3% of the wing chord length. The possible reason for the small aerodynamic effects of wing corrugation is that the wing operates at a large angle of attack and the flow is separated： the large angle of incidence dominates the corrugation in determining the flow around the wing, and for separated flow, the flow is much less sensitive to wing shape variation.

关键词： insect flapping forward flight wing corrugation aerodynamics

Unsteady aerodynamic forces and power requirements of a bumblebee in forward flight

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Acta Mechanica Sinica 2005年第3期21卷 207-217页

作者： Jianghao Wu Mao Sun Institute of Fluid Mechanics. Beijing University of Aeronautics & Astronautics Beijing 100083 China

Aerodynamic forces and power requirements in forward flight in a bumblebee （Bombus terrestris） were studied using the method of computational fluid dynamics. Actual wing kinematic data of free flight were used in the study （the speed ranges from 0 m/s to 4.5 m/s; advance ratio ranges from 0-0.66）. The bumblebee employs the delayed stall mechanism and the fast pitching-up rotation mechanism to produce vertical force and thrust. The leading-edge vortex does not shed in the translatory phase of the half-strokes and is much more concentrated than that of the fruit fly in a previous study. At hovering and low-speed flight, the vertical force is produced by both the half-strokes and is contributed by wing lift; at medium and high speeds, the vertical force is mainly produced during the downstroke and is contributed by both wing lift and wing drag. At all speeds the thrust is mainly produced in the upstroke and is contributed by wing drag. The power requirement at low to medium speeds is not very different from that of hovering and is relatively large at the highest speed （advance ratio 0.66）, i.e. the power curve is Jshaped. Except at the highest flight speed, storing energy elastically can save power up to 20%-30%. At the highest speed, because of the large increase of aerodynamic torque and the slight decrease of inertial torque （due to the smaller stroke amplitude and stroke frequency used）, the power requirement is dominated by aerodynamic power and the effect of elastic storage of energy on power requirement is limited.

关键词： Insect forward flight Unsteady aerodynamics Power Numerical flow simulation

Aerodynamic Interactions Between Wing and Body of a Model Insect in forward flight and Maneuvers

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Journal of Bionic Engineering 2013年第1期10卷 19-27页

作者： Bin Liang Mao Sun Ministry-of-Education Key Laboratory of Fluid Mechanics Beihang University Beoing 100191 P. R. China

The aerodynamic interactions between the body and the wings of a model insect in forward flight and maneuvers are studied using the method of numerically solving the Navier-Stokes equations over moving overset grids. Three cases are con- sidered, including a complete insect, wing pair only and body only. By comparing the results of these cases, the interaction effect between the body and the wing pair can be identified. The changes in the force and moment coefficients of the wing pair due to the presence of the body are less than 4.5% of the mean vertical force coefficient of the model insect; the changes in the aero- dynamic force coefficients of the body due to the presence of the wings are less than 5.0% of the mean vertical force coefficient of the model insect. The results of this paper indicate that in studying the aerodynamics and flight dynamics of a flapping insect in forward flight or maneuver, separately computing （or measuring） the aerodynamic forces and moments on the wing paig and on the body could be a good approximation.

关键词： insect wing-body aerodynamic interaction forward flight maneuvers Navier-Stokes simulation

Two- and Three-Dimensional Simulations of Beetle Hind Wing Flapping during Free forward flight

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Journal of Bionic Engineering 2013年第3期10卷 316-328页

作者： Tuyen Quang Le Tien Van Truong Hieu Trung Tran Soo Hyung Park Jin Hwan Ko Hoon Cheol Park Kwang Joon Yoon Doyoung Byun Korea Institute of Ocean Science and Technology PO Box 29 Ansan 425-600 Republic of Korea Department of Aerospace and Information Engineering Konkuk University Seoul Republic of Korea Department of Advanced Technology Fusion Konkuk University Seoul Republic of Korea Department of Mechanical Engineering Sungkyunkwan University Suwon440-746 Republic of Korea

Aerodynamic characteristic of the beetle, Trypoxylus dichotornus, which has a pair of elytra （forewings） and hind wings, is numerically investigated. Based on the experimental results of wing kinematics, two-dimensional （2D） and three-dimensional （3D） computational fluid dynamic simulations were carried out to reveal aerodynamic performance of the hind wing. The roles of the spiral Leading Edge Vortex （LEV） and the spanwise flow were clarified by comparing 2D and 3D simulations. Mainly due to pitching down of chord line during downstroke in highly inclined stroke plane, relatively high averaged thrust was produced in the free forward flight of the beetle. The effects of the local corrugation and the camber variation were also investigated for the beetle＇s hind wings. Our results show that the camber variation plays a significant role in improving both lift and thrust in the flapping. On the other hand, the local corrugation pattern has no significant effect on the aerodynamic force due to large angle of attack during flapping.

关键词： beetle flight forward flight three-dimensional simulation corrugation effect time-camber variation

Wing Kinematics, Aerodynamic Forces and Vortex-wake Structures in Fruit-flies in forward flight

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Journal of Bionic Engineering 2016年第3期13卷 478-490页

作者： XueguangMeng Mao Sun Institute of Fluid Mechanics Beijing University of Aeronautics and Astronautics Beijing 100191 China

Wing kinematics in forward-flying fruit-flies was measured using high-speed cameras and flows of the flapping wing were calculated numerically. The large lift and thrust coefficients produced by the wing were explained. The wing flaps along a forward-tilting stroke plane. In the starting portion of a half-stroke （an upstroke or downstroke）, the wing pitches down to a small pitch angle; during the mid portion （the wing has built up its speed）, it first fast pitches up to a large pitch angle and then maintains the pitch angle; in the ending portion, the wing pitches up further. A large aerodynamic force （normal to the wing surface） is produced during the mid portion of a half-stroke. The large force is produced by the fast-pitching-up rotation and delayed-stall mechanisms. As a result of the orientation of wing, the thrust that propels the insect is produced by the upstroke and the major part of the vertical force that supports the weight is produced by the downstroke. In producing the thrust the upstroke leaves a ＂vortex ring＂ that is almost vertical, and in producing the vertical force the downstroke leaves a ＂vortex ring＂ that is almost horizontal.

关键词： fruit-fly wing kinematics forward flight Navier-Stokes simulation vortex

Two-Dimensional Aerodynamic Models of Insect flight for Robotic Flapping Wing Mechanisms of Maximum Efficiency

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Journal of Bionic Engineering 2008年第1期5卷 1-11页

作者： Thien-Tong Nguyen Doyoung Byun Department of Aeronautical Engineering Hochiminh City University of Technology Hochiminh City Vietnam Department of Aerospace Engineering Konkuk University Seoul 143-701 Korea

In the ＂modified quasi-steady＂ approach, two-dimensional （2D） aerodynamic models of flapping wing motions are analyzed with focus on different types of wing rotation and different positions of rotation axis to explain the force peak at the end of each half stroke. In this model, an additional velocity of the mid chord position due to rotation is superimposed on the translational relative velocity of air with respect to the wing. This modification produces augmented forces around the end of each stroke. For each case of the flapping wing motions with various combination of controlled translational and rotational velocities of the wing along inclined stroke planes with thin figure-of-eight trajectory, discussions focus on lift-drag evolution during one stroke cycle and efficiency of types of wing rotation. This ＂modified quasi-steady＂ approach provides a systematic analysis of various parameters and their effects on efficiency of flapping wing mechanism. Flapping mechanism with delayed rotation around quarter-chord axis is an efficient one and can be made simple by a passive rotation mechanism so that it can be useful for robotic application.

关键词： bionics modified quasi-steady approach insect flight hovering forward flight