Abstract:
Leading edge vortex (LEV) formation is considered a dominant factor for
high lift production during insect flapping. Previous studies suggest that LEV
occupies the separation zone on suction side of the wing and does not shed even
after many chords of travel. The development of micro aerial vehicle (MAV)
inspired from nature is an active area of research. MAV operates at Reynolds
number 104
-105
; slightly higher than the insects Re range. The motivation behind
present research is to investigate whether “stall-absent” phenomenon manifests at
Re 34000, representative of MAV. Corrugated dragonfly airfoil with rectangular
wing planform is used and wing motion kinematics is restricted to azimuth rotation.
Three dimensional finite volume method Fluent is used to numerically solve time
dependent incompressible Navier-Stokes equations using pressure based solver.
Computed results at Re 34000 and 100,000, reveal the same phenomena of
leading edge vortex formation, as observed in case of insects. There is an intense
spanwise flow, comparable to chordwise velocity that ensures that the LEV does
not grow in size and sheds. Furthermore, parametric study is also conducted to see
the effect of angle of attack, acceleration duration, aspect ratio, and wing planform
on corrugated wing in sweeping motion. It was also observed that there is no
noticeable difference in aerodynamic efficiency of the wing, subjected to geometric
variation.
