Lined-duct acoustic filter
US4346781A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 9, 1980 |
| Grant date | Aug 31, 1982 |
| Priority date | — |
| Expiry date | Jun 9, 2000 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16L55/02
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A lined duct is divided into two parallel branches by means of a rigid partition. The phase speed of the fundamental mode in each branch depends on the liner configuration and can differ markedly from the free-space phase speed. When the liners in the two branches are not the same, the corresponding phase speeds will be different and a relative phase lag between the waves in the two branches results. This, in turn, leads to interference between these wave components (and their reflections) both at the exit and entrance of the parallel branch pair. This interference can be exploited for the purpose of obtaining a low-frequency attenuation which is substantially larger than the attenuation of the unpartitioned duct.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.