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.
