The application of finite element techniques to acoustic transmission in lined ducts with flow
Abstract
The finite element method (FEM) is used to analyze the propagation of sound in two-dimensional nonuniform ducts carrying a compressible subsonic mean flow. Galerkin and residual least squares (RLS) methods with natural and forced boundary conditions are considered. The accuracy of FEM results for the eigenvalue and transmission problems is assessed by comparison with alternative numerical schemes for nonuniform ducts. The results presented and those from associated investigations indicate that modal coupling is a significant feature of the acoustic field, especially at high Mach numbers. A multimodal model therefore appears to be essential if any reliable conclusions are to be drawn in the context of turbofan inlet regions. Improvements to the eigenvalue scheme following the implementation of higher-order Hermitian elements indicate a similar modification for the transmission problem.
- Publication:
-
American Institute of Aeronautics and Astronautics Conference
- Pub Date:
- March 1979
- Bibcode:
- 1979aiaa.confQ....A
- Keywords:
-
- Acoustic Propagation;
- Aeroacoustics;
- Ducted Flow;
- Jet Aircraft Noise;
- Linings;
- Turbofan Engines;
- Acoustic Ducts;
- Finite Element Method;
- Mach Number;
- Sound Fields;
- Acoustics