Lift from Spanwise Flow in Simple Flapping Wings

Spanwise flow contributes to lift in thin flat-plate zero-pitch-angle flapping wings in quiescent air. It is reasonable to maintain only the kinematics and mechanical complexity absolutely necessary in developing flapping-wing micro air vehicles. This study continues the quantification of the lift generated from a flapping motion of absolute minimum complexity thought to be capable of generating lift. A flapping-wing micro air vehicle with rectangular planform wings fabricated in-house (semispan aspect ratios from 1.5 to 4.0) was used to quantify the contributions to lift from flow along the span of wings at numerous points throughout the flapping cycle under a variety of operating conditions (3-6 Hz and Reynolds numbers of 6000-15,000). These experiments were performed for several aspect ratios for flat-plate and spanwise-cambered wings. The lift force was quantified experimentally using a force transducer and a high-speed camera. Digital particle image velocimetry was used to determine the lift contributions of spanwise flow to the total measured lift. Additionally, the presence of spanwise camber was shown to affect the transient lift behavior.

[1]  Peter Ifju,et al.  Three-Dimensional Averaged Flow Around Flexible Flapping Wings , 2009 .

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

[3]  J. Westerweel.  Digital particle image velocimetry: theory and application , 1993 .

[4]  C. Ellington.  The novel aerodynamics of insect flight: applications to micro-air vehicles. , 1999, The Journal of experimental biology.

[5]  Aaron Altman,et al.  Streamwise Vorticity in Simple Mechanical Flapping Wings , 2007 .

[6]  T. Daniel,et al.  The Journal of Experimental Biology 206, 2989-2997 © 2003 The Company of Biologists Ltd , 2003 .

[7]  Stacey A. Combes,et al.  Wing flexibility and design for animal flight , 2002 .

[8]  L. D. Alford,et al.  A New Investigation of Natural Flight Characteristics and Theory , 2004 .

[9]  R. Dudley.  The Biomechanics of Insect Flight: Form, Function, Evolution , 1999 .

[10]  M. Dickinson,et al.  Spanwise flow and the attachment of the leading-edge vortex on insect wings , 2001, Nature.

[11]  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.

[12]  M. Dickinson,et al.  Force production and flow structure of the leading edge vortex on flapping wings at high and low Reynolds numbers , 2004, Journal of Experimental Biology.

[13]  C. H. Greenewalt.  Dimensional relationships for flying animals , 1962 .

[14]  Fulvio Scarano,et al.  Non-intrusive load characterization of an airfoil using PIV , 2006 .

[15]  Akira Azuma,et al.  The Biokinetics of Flying and Swimming , 1992 .

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

[17]  Ismet Gursul,et al.  An Investigation of Vortex Flows over Low Sweep Delta Wings , 2003 .

[18]  A. R. Ennos.  INERTIAL AND AERODYNAMIC TORQUES ON THE WINGS OF DIPTERA IN FLIGHT , 1989 .

[19]  Thomas L. Daniel,et al.  Forward flapping flight from flexible fins , 1988 .

[20]  M. Dickinson,et al.  The control of flight force by a flapping wing: lift and drag production. , 2001, The Journal of experimental biology.

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