Aerodynamic interaction of collective plates in side-by-side arrangement

Abstract

In tip-reversal upstrokes of bird flight, primary feathers twist individually, separate from each other, and make gaps between them. Although this behavior was reported to allow individual feathers to function as individual airfoils, lift contribution of each feather in tip-reversal upstrokes and interaction of flow around feathers with gaps still remain unclear. To elucidate aerodynamic characteristics of each feather in tip-reversal upstrokes, we model feathers as collective plates and conduct numerical simulation at Reynolds number ($U_{\infty}t/c$) = 100. The angle of attack of the collective plates $\alpha$ is fixed at 90°, and the gap distance $d/c$ and the angle of attack of each plate $\theta$ are varied. Lift of the plates increases from the bottom plate to the top one. At high angle of attack of each plate, lift coefficient of the collective plates are higher than those of a single plate. The model can be used for micro air vehicle or nano air vehicle in that collective plates can have better aerodynamic performance than that of a single plate in terms of the lift. In addition, this study can give insights into understanding the principles of active flow control using multi-body system for the purpose of enhancing maneuverability.