Abstract
This study experimentally investigates aerodynamic characteristics and flow fields of a smooth owl-like airfoil without serrations and velvet structures. This biologically inspired airfoil design is intended to serve as the main-wing for low-Reynolds-number aircrafts such as micro air vehicles. Reynolds number dependency on aerodynamics is also evaluated at low Reynolds numbers. The results of the study show that the owl-like airfoil has high lift performance with a nonlinear lift increase due to the presence of a separation bubble on the suction side. A distinctive flow feature of the owl airfoil is a separation bubble on the pressure side at low angles of attack. The separation bubble switches location from the pressure side to the suction side as the angle of attack increases and is continuously present on the surface within a wide range of angles of attack. The Reynolds number dependency on the lift curves is insignificant, although differences in the drag curves are especially pronounced at high angles of attack. Eventually, we obtain the geometric feature of the owl-like airfoil to increase aerodynamic performance at low Reynolds numbers.
Highlights
Biomimetics includes the concepts and principles acquired from nature for application in science and engineering such as in aerodynamic and fluid control devices
This study experimentally investigates aerodynamic characteristics and flow fields of a smooth owl-like airfoil without serrations and velvet structures
Schmitz et al described an airfoil with geometric features that achieves high aerodynamic performance at low Reynolds numbers [9] [10], which coincides with the geometric features of the owl wing
Summary
Biomimetics includes the concepts and principles acquired from nature for application in science and engineering such as in aerodynamic and fluid control devices. Schmitz et al described an airfoil with geometric features that achieves high aerodynamic performance at low Reynolds numbers [9] [10], which coincides with the geometric features of the owl wing. This present study investigates the aerodynamic characteristics of an owl-like airfoil that approaches the flight Reynolds numbers of an owl wing. Kondo et al [12] conducted two-dimensional laminar analyses of the smooth owl-shape airfoil provided by Liu et al [8] at Re = 23,000 They investigated the basic aerodynamic characteristics and flow fields around the airfoil and compared that with the Ishii airfoil [13], which is considered the frontrunner candidate for the main-wing airfoil of the Japanese Mars airplane. Experimental investigations are required because the prediction accuracy of the reattachment point of the separation bubble is insufficient in the two-dimensional laminar analysis
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