Turbofan engine having variable geometry fan duct
US4155221A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 27, 1976 |
| Grant date | May 22, 1979 |
| Priority date | — |
| Expiry date | Dec 27, 1996 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF05D2300/431
- WIPO fieldEngines, pumps, turbines
- WIPO sectorMechanical engineering
Abstract
This invention is an improved turbofan engine having a variable geometry fan duct which reduces stator source noise emitted from the engine. Attached to the inner wall of the fan casing near the fan stators is a pneumatically actuated annular membrane having two operating positions. In the cruise position, the membrane is forced radially inward to press against the radially outermost tips of the fan stators. In the second position, used during approach and takeoff, the membrane is drawn against a recessed portion in the fan casing, thereby creating an annular passageway between the stator tips and the casing. When the membrane is in this position, turbulent flow from the rotor blade tips which would normally impinge on the stators is directed through the annular passageway.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.