Loading...
Please wait, while we are loading the content...
Similar Documents
An evaluation of active noise control in a cylindrical shell
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Lester, H. C. Silcox, R. J. Abler, S. B. |
| Copyright Year | 1987 |
| Description | The physical mechanisms governing the use of active noise control in an extended volume of a cylindrical shell are discussed. Measured data was compared with computer results from a previously derived analytical model based on an infinite shell theory. For both the analytical model and experiment, the radiation of the external monopoles is coupled to the internal acoustic field through the radial displacement of the thin, elastic cylindrical shell. An active noise control system was implemented in the cylinder using a fixed array of discrete monopole sources, all of which lie in the plane of the exterior noise sources. Good agreement between measurement and prediction was obtained for both internal pressure response and overall noise reduction. Attenuations in the source plane greater than 15 dB were recorded along with a uniformly quieted noise environment over the entire length of the experimental model. Results indicate that for extended axial forcing distributions or very low shell damping, axial arrays of control sources may be required. Finally, the Nyquist criteria for the number of azimuthal control sources is shown to provide for effective control over the full cylinder cross section. |
| File Size | 7429589 |
| Page Count | 27 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19870011361 |
| Archival Resource Key | ark:/13960/t0qr9q526 |
| Language | English |
| Publisher Date | 1987-02-01 |
| Access Restriction | Open |
| Subject Keyword | Acoustics Damping Cylindrical Shells Propellers Noise Reduction Aircraft Noise Elastic Shells Low Frequencies Transmission Loss Active Control Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
