| タイトル | A finite element algorithm for sound propagation in axisymmetric ducts containing compressible mean flow |
| 本文（外部サイト） | http://hdl.handle.net/2060/19770020928 |
| 著者（英） | Abrahamson, A. L. |
| 著者所属（英） | Wyle Labs., Inc. |
| 発行日 | 1977-06-01 |
| 言語 | eng |
| 内容記述 | An accurate mathematical model for sound propagation in axisymmetric aircraft engine ducts with compressible mean flow is reported. The model is based on the usual perturbation of the basic fluid mechanics equations for small motions. Mean flow parameters are derived in the absence of fluctuating quantities and are then substituted into the equations for the acoustic quantities which were linearized by eliminating higher order terms. Mean swirl is assumed to be zero from the restriction of axisymmetry. A linear rectangular serendipity element is formulated from these equations using a Galerkin procedure and assembled in a special purpose computer program in which the matrix map for a rectangular mesh was specifically coded. Representations of the fluctuating quantities, mean quantities and coordinate transformations are isoparametric. The global matrix is solved by foreward and back substitution following an L-U decomposition with pivoting restricted internally to the blocks. Results from the model were compared with results from several alternative analyses and yielded satisfactory agreement. |
| NASA分類 | ACOUSTICS |
| レポートNO | 77N27872
RR-50624
NASA-CR-145209 |
| 権利 | No Copyright |
| URI | https://repository.exst.jaxa.jp/dspace/handle/a-is/181776 |
