GB881974A - Improvements in noise suppression jet propulsion nozzle - Google Patents

Abstract

881,974. Jet-propulsion plant. GENERAL ELECTRIC CO. July 16, 1959 [July 21, 1958], No. 24465/59. Class 110 (3). A jet-propulsion nozzle comprising a fixed noise suppressor nozzle which is circumferentially corrugated with the crests and valleys of the corrugations respectively extending longitudinally of the nozzle, has an ejector shroud formed with a convoluted periphery conforming generally to the external configuration of the fixed noise suppressor for enveloping the exhaust gases issuing therefrom with slower moving secondary air. The noise suppressed jet-propulsion nozzle comprises a number of petal-like lobes 12 symmetrically distributed about a plug 13 of tear-drop formation. The radial depth of the lobes is greatest at the outlet planes and decreases in the upstream direction. The plug and lobes divide the outlet of the nozzle into a number of small discrete nozzles. The nozzle is surrounded by a shroud 11 which generally conforms to the external configuration of the nozzle to define therewith narrow opening 15. The trailing edge of the shroud extends a short distance downstream of the nozzle, preferably to a distance equal to approximately 0.4 of the diameter of an equivalent circular area of a discrete nozzle. The inner extremities of alternate troughs of the shroud are secured by brackets 16 to the lobes 12. Brackets 18, 19 provide additional support. The leading edge of the shroud is provided with a flexible sealing section 24 which engages the trailing edge of the engine nacelle 25. Secondary air from the engine intake or some other convenient point along the nacelle flows rearwardly between the engine casing and nacelle before being ejected through the opening 15.