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Derivation of formulations 1 and 1a of farassat
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Farassat, F. |
| Copyright Year | 2007 |
| Description | Formulations 1 and 1A are the solutions of the Ffowcs Williams-Hawkings (FW-H) equation with surface sources only when the surface moves at subsonic speed. Both formulations have been successfully used for helicopter rotor and propeller noise prediction for many years although we now recommend using Formulation 1A for this purpose. Formulation 1 has an observer time derivative that is taken numerically, and thus, increasing execution time on a computer and reducing the accuracy of the results. After some discussion of the Green's function of the wave equation, we derive Formulation 1 which is the basis of deriving Formulation 1A. We will then show how to take this observer time derivative analytically to get Formulation 1A. We give here the most detailed derivation of these formulations. Once you see the whole derivation, you will ask yourself why you did not do it yourself! |
| File Size | 539018 |
| Page Count | 25 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20070010579 |
| Archival Resource Key | ark:/13960/t9c58kg2q |
| Language | English |
| Publisher Date | 2007-03-01 |
| Access Restriction | Open |
| Subject Keyword | Acoustics Subsonic Speed Green's Functions Ffowcs Williams-hawkings Equation Aircraft Noise Wave Equations Derivation Aerodynamic Noise Aeroacoustics Noise Prediction 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 |
