Loading...
Please wait, while we are loading the content...
Similar Documents
Background noise levels measured in the nasa lewis 9- by 15-foot low-speed wind tunnel
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Woodward, Richard P. Dittmar, James H. Kee-Bowling, Bonnie Hall, David G. |
| Copyright Year | 1994 |
| Description | The acoustic capability of the NASA Lewis 9 by 15 Foot Low Speed Wind Tunnel has been significantly improved by reducing the background noise levels measured by in-flow microphones. This was accomplished by incorporating streamlined microphone holders having a profile developed by researchers at the NASA Ames Research Center. These new holders were fabricated for fixed mounting on the tunnel wall and for an axially traversing microphone probe which was mounted to the tunnel floor. Measured in-flow noise levels in the tunnel test section were reduced by about 10 dB with the new microphone holders compared with those measured with the older, less refined microphone holders. Wake interference patterns between fixed wall microphones were measured and resulted in preferred placement patterns for these microphones to minimize these effects. Acoustic data from a model turbofan operating in the tunnel test section showed that results for the fixed and translating microphones were equivalent for common azimuthal angles, suggesting that the translating microphone probe, with its significantly greater angular resolution, is preferred for sideline noise measurements. Fixed microphones can provide a local check on the traversing microphone data quality, and record acoustic performance at other azimuthal angles. |
| File Size | 7478316 |
| Page Count | 16 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19950011639 |
| Archival Resource Key | ark:/13960/t77t2ms8j |
| Language | English |
| Publisher Date | 1994-12-01 |
| Access Restriction | Open |
| Subject Keyword | Research And Support Facilities (air) Angular Resolution Noise Reduction Wind Tunnel Walls Low Speed Wind Tunnels Holders Noise Measurement Background Noise Microphones Anechoic Chambers Acoustic Properties Turbofans Noise Intensity Aerodynamic Interference Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
