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Noise reduction in a mach 5 wind tunnel with a rectangular rod-wall sound shield
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Beckwith, I. E. Creel Jr., T. R. Keyes, J. W. |
| Copyright Year | 1980 |
| Description | A rod wall sound shield was tested over a range of Reynolds numbers of 0.5 x 10 to the 7th power to 8.0 x 10 to the 7th power per meter. The model consisted of a rectangular array of longitudinal rods with boundary-layer suction through gaps between the rods. Suitable measurement techniques were used to determine properties of the flow and acoustic disturbance in the shield and transition in the rod boundary layers. Measurements indicated that for a Reynolds number of 1.5 x 10 to the 9th power the noise in the shielded region was significantly reduced, but only when the flow is mostly laminar on the rods. Actual nozzle input noise measured on the nozzle centerline before reflection at the shield walls was attenuated only slightly even when the rod boundary layer were laminar. At a lower Reynolds number, nozzle input noise at noise levels in the shield were still too high for application to a quiet tunnel. At Reynolds numbers above 2.0 x 10 the the 7th power per meter, measured noise levels were generally higher than nozzle input levels, probably due to transition in the rod boundary layers. The small attenuation of nozzle input noise at intermediate Reynolds numbers for laminar rod layers at the acoustic origins is apparently due to high frequencies of noise. |
| File Size | 2270902 |
| Page Count | 83 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19800018123 |
| Archival Resource Key | ark:/13960/t88h3f658 |
| Language | English |
| Publisher Date | 1980-06-01 |
| Access Restriction | Open |
| Subject Keyword | Fluid Mechanics And Heat Transfer Sound Propagation Nozzle Flow Laminar Flow Noise Reduction Reynolds Number Supersonic Wind Tunnels Wind Tunnel Tests Boundary Layer Transition Noise Measurement Boundary Layers Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Technical Report |
