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Relationship between aerodynamic forces, flow structures and wing camber for rotating insect wing planforms

Published online by Cambridge University Press:  30 July 2013

R. R. Harbig*
Affiliation:
Fluids Laboratory for Aeronautical and Industrial Research (FLAIR), Department of Mechanical and Aerospace Engineering, Monash University, Clayton, VIC 3800, Australia
J. Sheridan
Affiliation:
Fluids Laboratory for Aeronautical and Industrial Research (FLAIR), Department of Mechanical and Aerospace Engineering, Monash University, Clayton, VIC 3800, Australia
M. C. Thompson
Affiliation:
Fluids Laboratory for Aeronautical and Industrial Research (FLAIR), Department of Mechanical and Aerospace Engineering, Monash University, Clayton, VIC 3800, Australia
*
Email address for correspondence: [email protected]

Abstract

Wing deformation is observed during the flight of some insect species; however, the effect of these distorted wing shapes on the leading edge vortex (LEV) is not well understood. In this study, we investigate the effect of one of these deformation parameters, (rigid) wing camber, on the flow structures and aerodynamic forces for insect-like wings, using a numerical model of an altered fruit fly wing revolving at a constant angular velocity. Both positive and negative camber was investigated at Reynolds numbers of 120 and 1500, along with the chordwise location of maximum camber. It was found that negatively cambered wings produce very similar LEV structures to non-cambered wings at both Reynolds numbers, but high positive camber resulted in the formation of multiple streamwise vortices at the higher Reynolds number, which disrupt the development of the main LEV. Despite this, positively cambered wings were found to produce higher lift to drag ratios than flat or negatively cambered wings. It was determined that a region of low pressure near the wing’s leading edge, combined with the curvature of the wing’s upper surface in this region, resulted in a vertical tilting of the net force vector for positively cambered wings, which explains how insects can benefit from wing camber.

Type
Papers
Copyright
©2013 Cambridge University Press 

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Harbig et al. suplementary movie

Change in vortex structure throughout the simulation for 0%

Download Harbig et al. suplementary movie(Video)
Video 6.6 MB

Harbig et al. suplementary movie

-15%

Download Harbig et al. suplementary movie(Video)
Video 8 MB

Harbig et al. suplementary movie

and 15% camber wings (p/c = 0.5). Vortex structures are visualised using surfaces of constant Q criterion and are coloured by spanwise vorticity to indicate direction; blue is negative and green is positive. Images are taken perpendicular to the wing surface.

Download Harbig et al. suplementary movie(Video)
Video 6.1 MB