| タイトル | Validation of an Acoustic Impedance Prediction Model for Skewed Resonators |
| 本文（外部サイト） | http://hdl.handle.net/2060/20090020430 |
| 著者（英） | Howerton, Brian M.; Parrott, Tony L. |
| 著者所属（英） | NASA Langley Research Center |
| 発行日 | 2009-05-11 |
| 言語 | eng |
| 内容記述 | An impedance prediction model was validated experimentally to determine the composite impedance of a series of high-aspect ratio slot resonators incorporating channel skew and sharp bends. Such structures are useful for packaging acoustic liners into constrained spaces for turbofan noise control applications. A formulation of the Zwikker-Kosten Transmission Line (ZKTL) model, incorporating the Richards correction for rectangular channels, is used to calculate the composite normalized impedance of a series of six multi-slot resonator arrays with constant channel length. Experimentally, acoustic data was acquired in the NASA Langley Normal Incidence Tube over the frequency range of 500 to 3500 Hz at 120 and 140 dB OASPL. Normalized impedance was reduced using the Two-Microphone Method for the various combinations of channel skew and sharp 90o and 180o bends. Results show that the presence of skew and/or sharp bends does not significantly alter the impedance of a slot resonator as compared to a straight resonator of the same total channel length. ZKTL predicts the impedance of such resonators very well over the frequency range of interest. The model can be used to design arrays of slot resonators that can be packaged into complex geometries heretofore unsuitable for effective acoustic treatment. |
| NASA分類 | Acoustics |
| レポートNO | AIAA Paper 2009-3143
LF99-7894 |
| 権利 | Copyright, Distribution as joint owner in the copyright |
