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Cruise noise of counterrotation propeller at angle of attack in wind tunnel
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Dittmar, J. H. |
| Copyright Year | 1986 |
| Description | The noise of a counterrotation propeller at angle of attack was measured in the NASA Lewis 8- by 6-Foot Supersonic Wind Tunnel at cruise conditions. Noise increases of as much as 4 dB were measured at positive angles of attack on the tunnel side wall, which represented an airplane fuselage. These noise increases could be minimized or eliminated by operating the counterrotation propeller with the front propeller turning up-inboard. This would require oppositely rotating propellers on opposite sides of the airplane. Noise analyses at different bandwidths enabled the separate front- and rear-propeller tones, as well as the total noise, at each harmonic to be determined. A simplified noise model was explored to show how the observed circumferential noise patterns of the separate propeller tones might have occurred. The total noise pattern, which represented the sum of the front- and rear-propeller tones at a particular harmonic, showed trends that would be hard to interpret without the separate-tone results. Therefore it is important that counterrotation angle-of-attack noise data be taken in such a manner that the front- and rear-propeller tones can be separated. |
| File Size | 2917181 |
| Page Count | 35 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19870003819 |
| Archival Resource Key | ark:/13960/t2h759d4b |
| Language | English |
| Publisher Date | 1986-10-01 |
| Access Restriction | Open |
| Subject Keyword | Acoustics Harmonics Noise Reduction Aircraft Noise Contrarotating Propellers Wind Tunnel Tests Fuselages Mathematical Models Cruising Flight Wind Tunnel Walls Angle of Attack 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 |
