Positive and Negative Spanwise Flow Development on an Insect-Like Rotating Wing

This paper presents an experimental investigation of the spanwise flow development on an impulsively started rotating rectangular wing at 45 deg angle of attack. Reynolds numbers of 500 and 15,000 were studied, which correspond to insect and flapping-wing micro-air-vehicle scales, respectively. Stereoscopic particle image velocimetry flowfield measurements were taken at various spanwise locations and sweep angles (angle of rotation from start) on a motor-driven rectangular wing immersed in a seeded water tank. At both Reynolds numbers, the development of the flow was characterized by the formation of strong positive (root-to-tip) and negative (tip-to-root) spanwise flows, which lost strength toward the tip and root, respectively. The negative spanwise flow appeared to be created by the tip vortex, which accelerated fluid from beyond the tip to the root and turned a portion of the positive spanwise flow back on itself, inducing a secondary vortex inboard of the tip vortex and rotating in the opposite sense...

[1]  Mark V. Finnis,et al.  Planar visualization of vortical flows , 2006 .

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

[3]  C. Ellington,et al.  The three–dimensional leading–edge vortex of a ‘hovering’ model hawkmoth , 1997 .

[4]  M. Dickinson,et al.  Time-resolved reconstruction of the full velocity field around a dynamically-scaled flapping wing , 2006 .

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

[6]  M. Dickinson,et al.  The influence of wing–wake interactions on the production of aerodynamic forces in flapping flight , 2003, Journal of Experimental Biology.

[7]  J. Leishman,et al.  Phase-locked particle image velocimetry measurements of a flapping wing , 2006 .

[8]  J. Westerweel,et al.  Efficient detection of spurious vectors in particle image velocimetry data , 1994 .

[9]  Richard D. Keane,et al.  Theory of cross-correlation analysis of PIV images , 1992 .

[10]  R. Zbikowski,et al.  Experimental investigation of some aspects of insect-like flapping flight aerodynamics for application to micro air vehicles , 2009 .

[11]  C. Willert,et al.  Digital particle image velocimetry , 1991 .

[12]  Kevin Knowles,et al.  The leading-edge vortex and aerodynamics of insect-based flapping-wing micro air vehicles , 2009, The Aeronautical Journal (1968).

[13]  J. Gordon Leishman,et al.  Flow Visualization of Micro Air Vehicle Scaled Insect-Based Flapping Wings. , 2005 .

[14]  M. Gharib,et al.  On errors of digital particle image velocimetry , 1997 .

[15]  Markus Raffel,et al.  Particle Image Velocimetry: A Practical Guide , 2002 .

[16]  Gary D. Lock,et al.  Energy requirements for the flight of micro air vehicles , 2001, The Aeronautical Journal (1968).

[17]  P. C. Wilkins,et al.  Some unsteady aerodynamics relevant to insect-inspired flapping-wing micro air vehicles , 2008 .

[18]  Yuan Lu,et al.  Three-dimensional flow structures and evolution of the leading-edge vortices on a flapping wing , 2008, Journal of Experimental Biology.