The noise generating and suppressing characteristics of bio-inspired rough surfaces
I Clark, WJ Devenport, J Jaworski, C Daly… - 20th AIAA/CEAS …, 2014 - arc.aiaa.org
It is hypothesized that the structure of the down covering the flight feathers of larger species
of owls contributes to their ability to fly almost silently at frequencies above 1.6 kHz.
Microscope photographs of the down show that it consists of hairs that form a structure
similar to that of a forest. The hairs initially rise almost perpendicular to the feather surface
but then bend over in the flow direction to form a canopy with an open area ratio of about
70%. Experiments have been performed to examine the noise radiated by vertical filaments …
of owls contributes to their ability to fly almost silently at frequencies above 1.6 kHz.
Microscope photographs of the down show that it consists of hairs that form a structure
similar to that of a forest. The hairs initially rise almost perpendicular to the feather surface
but then bend over in the flow direction to form a canopy with an open area ratio of about
70%. Experiments have been performed to examine the noise radiated by vertical filaments …