A Study of Bio-Inspired Canopies for the Reduction of Roughness Noise
| dc.contributor.author | Clark, Ian Andrew | en |
| dc.contributor.committeechair | Devenport, William J. | en |
| dc.contributor.committeemember | Alexander, William Nathan | en |
| dc.contributor.committeemember | Paterson, Eric G. | en |
| dc.contributor.department | Aerospace and Ocean Engineering | en |
| dc.date.accessioned | 2015-01-10T09:00:23Z | en |
| dc.date.available | 2015-01-10T09:00:23Z | en |
| dc.date.issued | 2015-01-09 | en |
| dc.description.abstract | The wings of most species of owl have been shown to possess three unique physical attributes which allow them to hunt in effective silence: a comb of evenly-spaced bristles along the wing leading-edge; a compliant and porous fringe of feathers at the trailing-edge; and a velvety down material distributed over the upper wing surface. This investigation focuses on the last of the mechanisms as a means to reduce noise from flow over surface roughness. A microscopic study of several owl feathers revealed the structure of the velvety down to be very similar to that of a forest or a field of crops. Analogous surface treatments (suspended canopies) were designed which simulated the most essential geometric features of the velvety down material. The Virginia Tech Anechoic Wall-Jet Facility was used to perform far-field noise and surface pressure fluctuation measurements in the presence of various combinations of rough surfaces and suspended canopies. All canopies were demonstrated to have a strong influence on the surface pressure spectra, and attenuations of up to 30 dB were observed. In addition, all canopies were shown to have some positive effects on far-field noise, and optimized canopies yielded far-field noise reductions of up to 8 dB across all frequencies at which roughness noise was observed. This development represents a new passive method for roughness noise control with possibility for future optimization and application to engineering structures. | en |
| dc.description.degree | Master of Science | en |
| dc.format.medium | ETD | en |
| dc.identifier.other | vt_gsexam:4367 | en |
| dc.identifier.uri | http://hdl.handle.net/10919/51178 | en |
| dc.publisher | Virginia Tech | en |
| dc.rights | In Copyright | en |
| dc.rights.uri | http://rightsstatements.org/vocab/InC/1.0/ | en |
| dc.subject | Roughness Noise | en |
| dc.subject | Bio-Inspired | en |
| dc.subject | Noise Reduction | en |
| dc.subject | Noise Control | en |
| dc.subject | Canopies | en |
| dc.title | A Study of Bio-Inspired Canopies for the Reduction of Roughness Noise | en |
| dc.type | Thesis | en |
| thesis.degree.discipline | Aerospace Engineering | en |
| thesis.degree.grantor | Virginia Polytechnic Institute and State University | en |
| thesis.degree.level | masters | en |
| thesis.degree.name | Master of Science | en |
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