System and method for suppressing noise produced by rotors
US5217349A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 31, 1989 |
| Grant date | Jun 8, 1993 |
| Priority date | — |
| Expiry date | Aug 31, 2009 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T50/60
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
Disclosed is a system and method for suppressing rotor noise by distributing mass and momentum sources and sinks on the rotor blade. A source is located on the blade, and therefore has the directivity of moving, as opposed to a stationary source. Moreover, the motion of the blade with respect to the observer amplifies the sound from the source in a manner similar to the manner in which motion of the blade amplifies all other sources of noise associated with the rotating blade. Two sources can be used to cancel noise. The first source, created by ejecting air from or drawing air into the blade, is used to cancel the "load" portion of rotor noise. The second source, created by developing a radial force with a proplet, is used to cancel the "thickness" portion of rotor noise. More control can be achieved by time modulating the rate of suction or the amplitude of radial force developed by said proplet.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.