Meeting Abstract

104.6  Tuesday, Jan. 7 09:15  The effect of petiolation on the leading-edge vortex of an insect-like flapping wing PHILLIPS, N.; KNOWLES, K.; BOMPHREY, R.J.*; The Royal Veterinary College; The Royal Veterinary College; Cranfield University rbomphrey@rvc.ac.uk

In general, animal wing planforms are broad close to the wing hinge and taper towards the tip. However, in many insect species, such as craneflies, the wings are petiolated (on stalks) leaving a gap between the thorax and the effective wing base. The impact of this architecture on lift-generating flow is not yet known, but its implications for the insect are significant. More petiolated wings will confer certain aerobatic benefits, but incur additional energetic costs. We investigated the effect of varying wing petiolation on the flow fields generated by flapping wings and, in particular, the lift-augmenting leading edge vortex (LEV) – a key aerodynamic structure exploited by many insects, birds and bats. Experiments were accomplished using a custom-designed, mechanical flapping apparatus (the Flapperatus) that produces highly repeatable insect-like kinematics with an adjustable wing beat frequency up to 20 Hz in air. Stereoscopic Particle Image Velocimetry (stereo-PIV) was employed to reconstruct spatially-dense, three-dimensional, velocity measurements throughout a volume enclosing the wing at eleven time steps throughout a half stroke cycle. Our findings reveal the impact of petiolation on the structure, size and strength of the LEV.