Predicting and analyzing geometric and morphing wing characteristics of the Grey-Headed Albatross

Abstract

Geometric and aerodynamic properties of various avian species allow engineers and biologists to gain valuable insight into the evolutionary honing of the capabilities of natural flyers. Very little research has been done to establish reliable 3D models and detailed descriptions of the aerodynamic characteristics of the Grey-headed Albatross. Therefore, the purpose of this work was to determine the static and passively morphed geometric and aerodynamic characteristics of the Grey-headed Albatross. A laser scanned 3D point cloud of a Grey-headed Albatross wing specimen was used to obtain spanwise airfoils using the PARSEC method, a novel method to the field of avian wings. A single objective optimization study using a pseudo 2D computational fluid dynamics model was done on an averaged airfoil of the arm section of the Grey-headed Albatross to determine the maximum potential aerodynamic efficiency (lift-to-drag-ratio) at a Reynolds number of 2 × 105 . This delivered the first reliable estimate of the passive morphing that an avian wing undergoes. The optimized Grey-headed Albatross airfoil decreased in camber creating a more streamlined body when compared to the highly cambered static airfoil. The optimized airfoil exhibited a maximum lift-to-drag ratio of 44 (αactual = −0.5 ∘ ,

αgeometric = −11.5 ∘ ) when compared to the baseline airfoil with a lift-to-drag ratio of 3 (α =

16∘ ). The increase in lift-to-drag ratio was partly due to the drastic decrease in pressure drag from 0.395 to 0.029 between the static and optimized airfoil, a decrease by a factor of 13.6. The optimized airfoil geometry was similar to that of a 3D laser scan which was done on a GHA wing in the presence of airflow. The increase of the aerodynamic efficiency is consistent with the notion that Grey-headed Albatrosses are efficient flyers.