Experimental Study of Owl-Like Airfoil Aerodynamics at Low Reynolds Numbers

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.

Aerodynamic Analysis of Variable Camber-Morphing Airfoils with Substantial Camber Deflections

“…As for publications considering bio-inspired morphing wings at very low Reynolds numbers [14], they usually refer to micro Unmanned Aerial Vehicles (UAVs) (see Figure 1). Anoyoji et al [15] studied owl-like airfoils for low Reynolds number flights of Micro Air Vehicles (MAVs). The NACA0012 airfoil was compared with a smooth owl-like airfoil for Re = 23,000 − 60,000.…”

Flow Study on the Anemometers of the Perseverance Based on Towing Tank Visualization

“…Having studied the low and ultra-low Reynolds number spectrum, researchers tried to visualize the effect that the number had on the turbulence downstream of an airfoil [7,8], or the effect it had on the laminar separation bubble at the leading edge of an airfoil [9]. Others preferred to study the aerodynamics of some birds and insects, such as a dragonfly at Re below 8000 [10], or an owl [11], due to their interest in micro air vehicles with fixed wings. Having studied the behavior of aerodynamic structures (such as airfoils), there was interest in knowing what behavior the flow displays on bluff bodies at low Reynolds numbers [12].…”

Aeroacoustic Simulation of an Owl Wing Cross-section Using Computational Fluid Dynamics

“…They concluded that the owl airfoil has a higher lift/drag ratio compared to NACA0002, NACA0012, and the Ishii airfoil. Anyoji et al [19] performed experiments in the wind tunnel with an owl-like airfoil, where they visualized the flow and measured the lift and drag properties. Again, the high cambered airfoil (on the pressure side) showed a better lift/drag ratio compared to NACA0012.…”