| タイトル | Acoustic Treatment Design Scaling Methods |
| 本文（外部サイト） | http://hdl.handle.net/2060/20030063912 |
| 著者（英） | Kraft, R. E.; Seybert, A. F.; Beer, B.; Yu, J.; Clark, L.; Tathavadekar, P.; Parrott, T.; Jones, M.; Kwan, H. W. |
| 著者所属（英） | General Electric Aircraft Engines |
| 発行日 | 2003-01-07 |
| 言語 | eng |
| 内容記述 | The ability to design, build and test miniaturized acoustic treatment panels on scale model fan rigs representative of full scale engines provides not only cost-savings, but also an opportunity to optimize the treatment by allowing multiple tests. To use scale model treatment as a design tool, the impedance of the sub-scale liner must be known with confidence. This study was aimed at developing impedance measurement methods for high frequencies. A normal incidence impedance tube method that extends the upper frequency range to 25,000 Hz. without grazing flow effects was evaluated. The free field method was investigated as a potential high frequency technique. The potential of the two-microphone in-situ impedance measurement method was evaluated in the presence of grazing flow. Difficulties in achieving the high frequency goals were encountered in all methods. Results of developing a time-domain finite difference resonator impedance model indicated that a re-interpretation of the empirical fluid mechanical models used in the frequency domain model for nonlinear resistance and mass reactance may be required. A scale model treatment design that could be tested on the Universal Propulsion Simulator vehicle was proposed. |
| NASA分類 | Acoustics |
| レポートNO | NASA/CR-2003-212428/PHASE2
NAS 1.26:212428/PHASE2 |
| 権利 | Copyright, Distribution under U.S. Government purpose rights |
|
