A flow control mechanism in wing flapping with stroke asymmetry during insect forward flight

A theoretical modeling approach as well as an unsteady analytical method is used to study aerodynamic characteristics of wing flapping with asymmetric stroke-cycles in connection with an oblique stroke plane during insect forward flight. It is revealed that the aerodynamic asymmetry between the downstroke and the upstroke due to stroke-asymmetrical flapping is a key to understand the flow physics of generation and modulation of the lift and the thrust. Predicted results for examples of given kinematics validate more specifically some viewpoints that the wing lift is more easily produced when the forward speed is higher and the thrust is harder, and the lift and the thrust are generated mainly during downstroke and upstroke, respectively. The effects of three controlling parameters, i.e. the angles of tilted stroke plane, the different downstroke duration ratios, and the different angles of attack in both down- and up-stroke, are further discussed. It is found that larger oblique angles of stroke planes generate larger thrust but smaller lift; larger downstroke duration ratios lead to larger thrust, while making little change in lift and input aerodynamic power; and again, a small increase of the angle of attack in downstroke or upstroke may cause remarkable changes in aerodynamic performance in the relevant stroke.

[1]  T. Weis-Fogh.  Quick estimates of flight fitness in hovering animals , 1973 .

[2]  J. Wu.  Theory for Aerodynamic Force and Moment in Viscous Flows , 1981 .

[3]  C. Ellington.  The Aerodynamics of Hovering Insect Flight. III. Kinematics , 1984 .

[4]  C. Ellington.  The Aerodynamics of Hovering Insect Flight. II. Morphological Parameters , 1984 .

[5]  R. Wootton.  THE MECHANICAL DESIGN OF INSECT WINGS , 1990 .

[6]  D. Houlihan,et al.  Advances in Comparative and Environmental Physiology , 1991, Advances in Comparative and Environmental Physiology.

[7]  M. Dickinson,et al.  UNSTEADY AERODYNAMIC PERFORMANCE OF MODEL WINGS AT LOW REYNOLDS NUMBERS , 1993 .

[8]  Adrian L. R. Thomas,et al.  Leading-edge vortices in insect flight , 1996, Nature.

[9]  D. Grodnitsky,et al.  Form and Function of Insect Wings: The Evolution of Biological Structures , 1999 .

[10]  M. Dickinson,et al.  Wing rotation and the aerodynamic basis of insect flight. , 1999, Science.

[11]  Z. J. Wang.  Vortex shedding and frequency selection in flapping flight , 2000, Journal of Fluid Mechanics.

[12]  Z. J. Wang.  Two dimensional mechanism for insect hovering , 2000 .

[13]  T. Y. Wu.  On theoretical modeling of aquatic and aerial animal locomotion , 2002 .

[14]  Mao Sun,et al.  Lift and power requirements of hovering flight in Drosophila virilis. , 2002, The Journal of experimental biology.

[15]  Mao Sun,et al.  Unsteady aerodynamic force generation by a model fruit fly wing in flapping motion. , 2002, The Journal of experimental biology.

[16]  R. Zbikowski.  On aerodynamic modelling of an insect–like flapping wing in hover for micro air vehicles , 2002, Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.

[17]  Yu Yongliang,et al.  An analytic approach to theoretical modeling of highly unsteady viscous flow excited by wing flapping in small insects , 2003 .

[18]  S. N. Fry,et al.  The Aerodynamics of Free-Flight Maneuvers in Drosophila , 2003, Science.

[19]  Mao Sun,et al.  Aerodynamic force generation and power requirements in forward flight in a fruit fly with modeled wing motion , 2003, Journal of Experimental Biology.