| タイトル | An Experimental Investigation of Jet Noise from Septa Nozzles |
| 本文（外部サイト） | http://hdl.handle.net/2060/20170000224 |
| 著者（英） | Bridges, J. E.; Fagan, A. F.; Brown, C. A.; Zaman, K. B. M. Q. |
| 著者所属（英） | NASA Glenn Research Center |
| 発行日 | 2016-05-30 |
| 言語 | eng |
| 内容記述 | Results of an experimental study with a large aspect ratio rectangular nozzle, divided into multiple compartments or septa, as pertinent to distributed propulsion, are presented. Noise measurements at high-subsonic conditions show that the nozzle with the septa is quieter than the corresponding baseline nozzle without the septa. At relatively lower Mach numbers a high-frequency tone is heard. This is shown to be due to Karmann vortex shedding from the trailing edge of the partitions that separate a septum from the adjacent ones. Flowfield measurements for a six septa case show that the cellular flow structure, issuing from the nozzle, goes through a curious coalescence with increasing downstream distance (x) from the nozzle. Adjacent cells pair to yield a three-cell structure by x/D =2, where D is the equivalent diameter of the baseline nozzle. By about x/D =16, both the septa case and the baseline case evolve to yield axisymmetric flowfields. |
| NASA分類 | Aeronautics (General) |
| レポートNO | GRC-E-DAA-TN30991 |
| 権利 | No Copyright |
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