Aerodynamics of revolving bristled wings at low Reynolds Number

Abstract

Thrips are one among the wide variety of tiny insects (body length under 2 mm) that are capable of flight at Reynolds number on the order of 10. Unlike larger insects like dragonflies and fruit flies, the wing structure of thrips is composed of a thin membrane with long bristles at the fringes. Previous studies have shown that bristled wings produce less drag when compared to equivalent non-bristled (solid) wings during the start of downstroke. However, it still remains unclear as to how the smallest flying insects with bristled wings are capable of sustained flight during rest of the downstroke, suggesting a need for further research. In this study, we examined the aerodynamic force generation on a revolving bristled wing model as a function of varying angle of attack. A robotic platform was used to revolve physical models of non-bristled and bristled wing models and strain gauges were used to acquire lift and drag forces. We hypothesize that bristles would show diffuse vorticity patterns in the leading and trailing edge vortices when compared to an equivalent solid wing, which in turn can help in maintaining lift generation across the cycle. Particle image velocimetry (PIV) will be used to visualize the flow along chordwise planes.