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<p>Investigating different airfoils at low Reynolds numbers is crucial due to their wide range of applications such as wind turbines, tidal turbines, UAVs, noise-sensitive drones, and small-scale air and underwater vehicles. This study focuses on comparing the flow physics around the owl airfoil, renowned for its silent flight, with conventional airfoils and a hawk airfoil, known for noisy flight. Detached eddy simulation (DES) and smoke flow visualization techniques were employed to examine the flow fields around four airfoils: owl, hawk, NACA 0012, and NACA 4412. Experiments were conducted at chord-based Reynolds numbers of 21.5 × 10<sup>3</sup>, 32.5 × 10<sup>3</sup>, and 43.5 × 10<sup>3</sup> for various angles of attack. Wind tunnel testing revealed that the owl airfoil experienced significantly less turbulence phenomena, such as flow separation, compared to the other airfoils at low Reynolds numbers. This reduction in turbulence correlates with lower aerodynamic noise production during gliding flight. Furthermore, at angles of attack of AOA = 4° and AOA = 8°, the owl airfoil exhibits more attached flow on the upper surface. Additionally, DES simulations show that the turbulence structure in the near wake is more favorable for the owl airfoil, while in the far wake, the NACA 0012 airfoil performs better.</p>

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Flow Physics of Bio-inspired Airfoils Using Experimental and DES Methods at Reynolds Numbers Below 44 × 103

  • 期刊论文

  • 发表日期：

    2025年10月22日

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  • M. Kazemi,
  • M. Mani,
  • H. Rezaei,
  • P. Ghanooni

摘要

Investigating different airfoils at low Reynolds numbers is crucial due to their wide range of applications such as wind turbines, tidal turbines, UAVs, noise-sensitive drones, and small-scale air and underwater vehicles. This study focuses on comparing the flow physics around the owl airfoil, renowned for its silent flight, with conventional airfoils and a hawk airfoil, known for noisy flight. Detached eddy simulation (DES) and smoke flow visualization techniques were employed to examine the flow fields around four airfoils: owl, hawk, NACA 0012, and NACA 4412. Experiments were conducted at chord-based Reynolds numbers of 21.5 × 103, 32.5 × 103, and 43.5 × 103 for various angles of attack. Wind tunnel testing revealed that the owl airfoil experienced significantly less turbulence phenomena, such as flow separation, compared to the other airfoils at low Reynolds numbers. This reduction in turbulence correlates with lower aerodynamic noise production during gliding flight. Furthermore, at angles of attack of AOA = 4° and AOA = 8°, the owl airfoil exhibits more attached flow on the upper surface. Additionally, DES simulations show that the turbulence structure in the near wake is more favorable for the owl airfoil, while in the far wake, the NACA 0012 airfoil performs better.