| タイトル | Improved Inlet Noise Attenuation by Alteration of Boundary Layer Profiles |
| 本文（外部サイト） | http://hdl.handle.net/2060/20040139251 |
| 著者（英） | Jones, Michael G.; Nark, Douglas M.; Mani, Ramani; Luedke, Jon |
| 著者所属（英） | NASA Langley Research Center |
| 発行日 | 2004-01-01 |
| 言語 | eng |
| 内容記述 | Acoustic liners are an essential component of technology used to reduce aircraft engine noise. Flow affects attenuation due to the liner in several ways, one of which is that boundary layers adjacent to the liner refract the sound. In the case of inlet noise, the boundary layer causes sound to be refracted away from the liner, thus degrading attenuation. A concept to improve attenuation by the liner by alteration of inlet boundary layer profiles is presented. The alteration of profiles is achieved by inlet blowing. Computational fluid dynamics and duct mode propagation theory for ducts carrying a parallel sheared flow have been used to design experiments to explore such a possibility in the NASA Langley Research Center Grazing Incidence Tube using an inlet blowing scheme developed at General Electric Global Research. The effects of inlet blowing on two liner configurations were evaluated. Calculated results will be shown for blowing ratios (injected flow/duct flow) of approximately 12% and frequencies up to 3 kHz. These results emphasize changes of attenuation achieved by blowing for the two liners. Experimental results of measured flow profiles (with and without blowing) in the Grazing Incidence Tube, and of corresponding changes in attenuation by the liner due to blowing will be presented. |
| NASA分類 | Aircraft Design, Testing and Performance |
| 権利 | Copyright, Distribution as joint owner in the copyright |
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