Patent ID: 8579225
Filing Date: 2013-11-12
Classification: F02C,F02K

Abstract:
1. A device for acoustically treating the noise emitted by a bypass turbojet, the device comprising: a primary cowl for surrounding a central core of the turbojet and including an inner annular acoustic treatment panel placed in an outer surface of the primary cowl; and a secondary cowl surrounding the primary cowl to co-operate therewith to define an annular channel for passing a cold flow from the turbojet, the secondary cowl including an outer annular acoustic treatment panel placed in an inner surface of the secondary cowl, the outer panel facing the inner panel and extending axially over a same length as the inner panel; wherein each of the inner and outer panels are subdivided to include respective central panel portions facing each other and extending axially over a common predetermined length, a length of the central panel portions being in a range of one-fifth to four-fifths of a total length of the panels, and a ratio of an acoustic resistance of the central panel portion of the outer panel to an acoustic resistance of the central panel portion of the inner panel being asymmetric and not less than 2.