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Time-dependent parabolic finite difference formulation for harmonic sound propagation in a two-dimensional duct with flow
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Kreider, Kevin L. Baumeister, Kenneth J. |
| Copyright Year | 1996 |
| Description | An explicit finite difference real time iteration scheme is developed to study harmonic sound propagation in aircraft engine nacelles. To reduce storage requirements for future large 3D problems, the time dependent potential form of the acoustic wave equation is used. To insure that the finite difference scheme is both explicit and stable for a harmonic monochromatic sound field, a parabolic (in time) approximation is introduced to reduce the order of the governing equation. The analysis begins with a harmonic sound source radiating into a quiescent duct. This fully explicit iteration method then calculates stepwise in time to obtain the 'steady state' harmonic solutions of the acoustic field. For stability, applications of conventional impedance boundary conditions requires coupling to explicit hyperbolic difference equations at the boundary. The introduction of the time parameter eliminates the large matrix storage requirements normally associated with frequency domain solutions, and time marching attains the steady-state quickly enough to make the method favorable when compared to frequency domain methods. For validation, this transient-frequency domain method is applied to sound propagation in a 2D hard wall duct with plug flow. |
| File Size | 857115 |
| Page Count | 18 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19970010251 |
| Archival Resource Key | ark:/13960/t46q6wg47 |
| Language | English |
| Publisher Date | 1996-11-01 |
| Access Restriction | Open |
| Subject Keyword | Acoustics Wave Equations Engine Inlets Boundary Conditions Nacelles Aircraft Engines Real Time Operation Ducted Flow Time Dependence Sound Propagation Iterative Solution Harmonic Excitation Finite Difference Theory Sound Fields Time Marching Aeroacoustics Hyperbolic Differential Equations Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Technical Report |
