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A computational study of the wing-wing and wing-body interactions of a model insect

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Acta Mechanica Sinica 2009年第4期25卷 421-431页

作者： Xin Yu Mao Sun Institute of Applied Physics and Computational Mathematics Beihang University 100191 Beijing China Institute of Fluid Mechanics Beihang University 100191 Beijing China

The aerodynamic interaction between the contralateral wings and between the body and wings of a model insect are studied, by using the method of numerically solving the Navier-Stokes equations over moving overset grids, under typical hovering and forward flight conditions. both the interaction between the contralateral wings and the interaction between the body and wings are very weak, e.g. at hovering, changes in aerodynamic forces of a wing due to the present of the other wing are less than 3% and changes in aerodynamic forces of the wings due to presence of the body are less than 2%. The reason for this is as following. During each down- or up-stroke, a wing produces a vortex ring, which induces a relatively large jet-like flow inside the ring but very small flow outside the ring. The vortex rings of the left and right wings are on the two sides of the body. Thus one wing is outside vortex ring of the other wing and the body is outside the vortex rings of the left and right wings, resulting in the weak interactions.

关键词： Insect Aerodynamics Wing/winginteraction Wing/body interaction

Stabilization control of a hovering model insect:lateral motion

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Acta Mechanica Sinica 2011年第5期27卷 823-832页

作者： Yan-Lai Zhang Mao Sun Ministry-of-Education Key Laboratory of Fluid Mechanics Beihang University 100191 Beijing China

Our previous study shows that the lateral disturbance motion of a model drone fly does not have inherent stability （passive stability）,because of the existence of an unstable divergence *** drone flies are observed to fly *** active control must be applied to stabilize the *** this study,we investigate the lateral stabilization control of the model drone *** method of computational fluid dynamics is used to compute the lateral control derivatives and the techniques of eigenvalue and eigenvector analysis and modal decomposition are used for solving the equations of *** analysis shows that although inherently unstable,the lateral disturbance motion is *** feeding back the state variables （*** translation velocity,yaw rate,roll rate and roll angle,which can be measured by the sensory system of the insect） to produce anti-symmetrical changes in stroke amplitude and/or in angle of attack between the left and right wings,the motion can be stabilized,explaining why the drone flies can fly stably even if the flight is passively unstable.

关键词： Hovering drone fly Lateral motion Flight stability Stabilization control Modal analysis

Dynamic flight stability of a hovering model insect:lateral motion

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Acta Mechanica Sinica 2010年第2期26卷 175-190页

作者： Yanlai Zhang Mao Sun Ministry-of-Education Key Laboratory of Fluid Mechanics Institute of Fluid Mechanics Beihang University 100191 Beijing China

The lateral dynamic flight stability of a hovering model insect （dronefly） was studied using the method of computational fluid dynamics to compute the stability derivatives and the techniques of eigenvalue and eigenvector analysis for solving the equations of motion. The main results are as following. （i） Three natural modes of motion were identified： one unstable slow divergence mode （mode 1）, one stable slow oscillatory mode （mode 2）, and one stable fast subsidence mode （mode 3）. Modes 1 and 2 mainly consist of a rotation about the horizontal longitudinal axis （x-axis） and a side translation; mode 3 mainly consists of a rotation about the x-axis and a rotation about the vertical axis. （ii） Approximate analytical expressions of the eigenvalues are derived, which give physical insight into the genesis of the natural modes of motion. （iii） For the unstable divergence mode, td, the time for initial disturbances to double, is about 9 times the wingbeat period （the longitudinal motion of the model insect was shown to be also unstable and td of the longitudinal unstable mode is about 14 times the wingbeat period）. Thus, although the flight is not dynamically stable, the instability does not grow very fast and the insect has enough time to control its wing motion to suppress the disturbances.

关键词： Insect Dynamic flight stability Hovering ·Lateral motion Natural modes of motion

Wing/body kinematics measurement and force and moment analyses of the takeoff flight of fruitflies

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Acta Mechanica Sinica 2014年第4期30卷 495-506页

作者： Mao-Wei Chen Mao Sun Ministry-of-Education Key Laboratory of Fluid Mechanics Beihang University

In the paper, we present a detailed analysis of the takeoff mechanics of fruitflies which perform voluntary takeoff flights. Wing and body kinematics of the insects during takeoff were measured using based on the measured data, high-speed video techniques. inertia force acting on the insect was computed and aerodynamic force and moment of the wings were calculated by the method of computational fluid dynamics. Subtracting the aerodynamic force and the weight from the inertia force gave the leg force. The following has been shown. In its voluntary takeoff, a fruitfly jumps during the first wingbeat and becomes airborne at the end of the first wingbeat. When it is in the air, the fly has a relatively large ＂initial＂ pitch-up rotational velocity （more than 5 000~/s） resulting from the jumping, but in about 5 wingbeats, the pitch-up rotation is stopped and the fly goes into a quasi-hovering flight. The fly mainly uses the force of jumping legs to lift itself into the air （the force from the flapping wings during the jumping is only about 5%-10% of the leg force）. The main role played by the flapping wings in the takeoff is to produce a pitch-down moment to nullify the large ＂initial＂ pitch-up rotational velocity （otherwise, the fly would have kept pitching-up and quickly fallen down）.

关键词： Fruitfly· Takeoff flight ·body and wing kine-matics Aerodynamic and leg forces

Dynamic flight stability of hovering model insects:theory versus simulation using equations of motion coupled with Navier-Stokes equations

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Acta Mechanica Sinica 2010年第4期26卷 509-520页

作者： Yan-Lai Zhang Mao Sun Ministry-of-Education Key Laboratory of Fluid Mechanics Institute of Fluid Mechanics Beihang University 100191 Beijing China

In the present paper, the longitudinal dynamic flight stability properties of two model insects are predicted by an approximate theory and computed by numerical sim- ulation. The theory is based on the averaged model （which assumes that the frequency of wingbeat is sufficiently higher than that of the body motion, so that the flapping wings＇ degrees of freedom relative to the body can be dropped and the wings can be replaced by wingbeat-cycle-average forces and moments）; the simulation solves the complete equations of motion coupled with the Navier-Stokes equations. Comparison between the theory and the simulation provides a test to the validity of the assumptions in the theory. One of the insects is a model dronefly which has relatively high wingbeat frequency （164 Hz） and the other is a model hawkmoth which has relatively low wingbeat frequency （26 Hz）. The results show that the averaged model is valid for the hawkmoth as well as for the dronefly. Since the wingbeat frequency of the hawkmoth is relatively low （the characteristic times of the natural modes of motion of the body divided by wingbeat period are relatively large） compared with many other insects, that the theory based on the averaged model is valid for the hawkmoth means that it could be valid for many insects.

关键词： Insect Hovering Dynamic flight stability Averaged model Equations-of-motion Navier-Stokes simulation

Robust fault detection and diagnosis for uncertain nonlinear systems

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Journal of Systems Engineering and Electronics 2009年第5期20卷 1031-1036页

作者： Wang Wei Tahir Hameed Ren Zhang Zhou Kemin School of Automation Science and Electrical Engineering Beihang Univ. Beijing 100191 P. R. China Dept. of Electrical and Computer Engineering Louisiana State Univ. Baton Rouge LA 70803 USA

This paper considers robust fault detection and diagnosis for input uncertain nonlinear systems. It proposes a multi-objective fault detection criterion so that the fault residual is sensitive to the fault but insensitive to the uncertainty as much as possible. Then the paper solves the proposed criterion by maximizing the smallest singular value of the transformation from faults to fault detection residuals while minimizing the largest singular value of the transformation from input uncertainty to the fault detection residuals. This method is applied to an aircraft which has a fault in the left elevator or rudder. The simulation results show the proposed method can detect the control surface failures rapidly and efficiently.

关键词： nonlinear system robust fault detection and diagnosis singular value flight control system.

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

Parameter vertex method and its parallel solution for evaluating the dynamic response bounds of structures with interval parameters

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Science China(Physics,Mechanics & Astronomy) 2018年第6期61卷 62-74页

作者： ZhiPing Qiu Pengbo Wang Institute of Solid Mechanics Beihang University Beijing 100191 China

In this article, we propose a parameter vertex method to determine the upper and lower bounds of the dynamic response of structures with interval parameters, which can be regarded as an extension of the matrix vertex method proposed by Qiu and Wang. The matrix vertex method requires considerable computation time and encounters the dependency problem in practice,thereby limiting its application in engineering. The proposed parameter vertex method can avoid the dependency problem, and the number of possible vertex combinations in the proposed method is significantly less than that in the matrix vertex *** parameter vertex method requires that each matrix element in the dynamic differential equation is monotonic with respect to the uncertain parameter, and that the dynamic response reaches its extreme value when the uncertain parameter is at its *** further reduce the runtime, both vertical and transversal parallel algorithms are introduced and integrated into the parameter vertex method to improve its computational efficiency. Two numerical examples are presented to demonstrate the proposed method combined with both parallel algorithms. The performances of the two parallel algorithms are thoroughly studied. The parameter vertex method combined with parallel algorithm can be used for large-scale computing.

关键词： parameter vertex method dynamic response interval parameter parallel algorithm upper and lower bounds

Interval analysis of transient temperature field with uncertain-but-bounded parameters

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Science China(Physics,Mechanics & Astronomy) 2014年第10期57卷 1959-1966页

作者： WANG Chong QIU ZhiPing Institute of Solid Mechanics Beihang University

based on the traditional finite volume method, a new numerical technique is presented for the transient temperature field prediction with interval uncertainties in both the physical parameters and initial/boundary conditions. New stability theory applicable to interval discrete schemes is developed. Interval ranges of the uncertain temperature field can be approximately yielded by two kinds of parameter perturbation methods. Different order Neumann series are adopted to approximate the interval matrix inverse. by comparing the results with traditional Monte Carlo simulation, a numerical example is given to demonstrate the feasibility and effectiveness of the proposed model and methods.

关键词： finite volume method temperature field prediction interval uncertainties stability theory parameter perturbationmethod