Vortex interaction of tandem pitching and plunging plates: a two-dimensional model of hovering dragonfly-like flight

The force evolution and associated vortex dynamics on a nominal two-dimensional tandem pitching and plunging configuration inspired by hovering dragonfly-like flight have been investigated experimentally using time-resolved particle image velocimetry. The aerodynamic forces acting on the flat plates have been determined using a classic control-volume approach, i.e. a momentum balance. It was found that only the tandem phasing of ψ = 90° was capable of generating similar levels of thrust when compared to the single-plate reference case. For this tandem configuration, however, a much more constant thrust generation was developed over the cycle. Further examination showed that the force and vortex development on the fore-plate was unaffected by the tandem configuration and that nearly all variations in performance could be attributed to the vortex interaction on the hind-plate. By calculating the trajectory and strength of the hind-plate's trailing-edge vortex, the chain-like vortex interaction mechanism responsible for improved performance at ψ = 90° could be identified. The underlying result from this study suggests that the dominant vortex interaction in dragonfly flight is two dimensional and that the spanwise flow generated by root-flapping kinematics is not entirely necessary for efficient propulsion but potentially due to evolutionary restrictions in nature.

[1]  K. Isogai,et al.  Unsteady Three -Dimensional Viscous Flow Simulation of a Dragonfly Hovering , 2004 .

[2]  Alain Farcy,et al.  Characterization of vortical structures and loads based on time-resolved PIV for asymmetric hovering flapping flight , 2009 .

[3]  F. Lehmann,et al.  The fluid dynamics of flight control by kinematic phase lag variation between two robotic insect wings , 2004, Journal of Experimental Biology.

[4]  Mao Sun,et al.  Aerodynamic interactions of two airfoils in unsteady motion , 2001 .

[5]  Mao Sun,et al.  A computational study of the aerodynamics and forewing-hindwing interaction of a model dragonfly in forward flight , 2005, Journal of Experimental Biology.

[6]  Adrian L. R. Thomas,et al.  Dragonfly flight: free-flight and tethered flow visualizations reveal a diverse array of unsteady lift-generating mechanisms, controlled primarily via angle of attack , 2004, Journal of Experimental Biology.

[7]  John O. Dabiri,et al.  On the estimation of swimming and flying forces from wake measurements , 2005, Journal of Experimental Biology.

[8]  Guillermo Rein,et al.  44th AIAA Aerospace Sciences Meeting and Exhibit , 2006 .

[9]  F. Lehmann.  When wings touch wakes: understanding locomotor force control by wake–wing interference in insect wings , 2008, Journal of Experimental Biology.

[10]  Mao Sun,et al.  A computational study of the aerodynamic forces and power requirements of dragonfly (Aeschna juncea) hovering , 2004, Journal of Experimental Biology.

[11]  D. E. Alexander.  Unusual Phase Relationships Between The Forewings And Hindwings In Flying Dragonflies , 1984 .

[12]  Fulvio Scarano,et al.  Evaluation of integral forces and pressure fields from planar velocimetry data for incompressible and compressible flows , 2007 .

[13]  F. Lehmann.  Wing–wake interaction reduces power consumption in insect tandem wings , 2009 .

[14]  D. Rockwell,et al.  FORCE PREDICTION BY PIV IMAGING: A MOMENTUM-BASED APPROACH , 1997 .

[15]  Flavio Noca,et al.  Measuring instantaneous fluid dynamic forces on bodies, using only velocity fields and their derivatives , 1997 .

[16]  A. Azuma,et al.  Flight Performance of a Dragonfly , 1988 .

[17]  Jürgen Kompenhans,et al.  Particle Image Velocimetry - A Practical Guide (2nd Edition) , 2007 .

[18]  Manabu Yamamoto,et al.  Direct Measurement of Unsteady Fluid Dynamic Forces for a Hovering Dragonfly , 2005 .

[19]  Fritz-Olaf Lehmann,et al.  Phasing of dragonfly wings can improve aerodynamic efficiency by removing swirl , 2008, Journal of The Royal Society Interface.

[20]  C. Tropea,et al.  Measurement of parallel blade–vortex interaction at low Reynolds numbers , 2010 .

[21]  M. Yamamoto.  Measurement of unsteady fluid dynamic force for a mechanical dragonfly model , 2005 .

[22]  F. Noca,et al.  A COMPARISON OF METHODS FOR EVALUATING TIME-DEPENDENT FLUID DYNAMIC FORCES ON BODIES, USING ONLY VELOCITY FIELDS AND THEIR DERIVATIVES , 1999 .