GB859994A - Noise suppressor for jet propulsion engines - Google Patents

Abstract

859,994. Jet-propulsion nozzles. BOEING AIRPLANE CO. June 20, 1958, No. 26364/60. Divided out of 859,993. Class 110 (3). A jet-propulsion engine having a propulsion nozzle is provided with noise suppression means comprising a plurality of stream divider elements 246 of generally plate-like form mounted on the nozzle so as to extend inwardly from the periphery of the exit thereof at spaced-apart locations therearound and disposed generally perpendicularly to the direction of gas discharge, the elements having openings 246c therein which allow a limited flow of discharge gases therethrough.for admixture with ambient air which is drawn inwardly across the downstream faces of the elements by the gas flow therebetween. The propulsion nozzle shown comprises a cylindrical duct 36 at the downstream end of which are pivoted overlapping flaps 36<SP>1</SP>a, 36<SP>1</SP>b, which may be swung inwardly or outwardly to vary the area of the nozzle outlet. The stream divider elements 246, which are of trapezoidal form with rearwardly-projecting flanges 246a, 246b, are pivotally mounted at the downstream edges of the pivoted flaps 36<SP>1</SP>a, the flaps 246 being shown in their projected positions and the flaps 36<SP>1</SP>a, 36<SP>1</SP>b in their maximum outlet area positions. The divider elements 246 are formed with arms 54 which are connected by means of links 56 and 28 to an actuating-device 58, operation of which moves the links 28 and 56 rearwardly from the position shown, so causing the divider element 246 to swing forwardly and outwardly into a retracted position lying against the inner face of the pivoted flap 36<SP>1</SP>a. Continued rearward movement of the link 56 causes the cam 561 thereon to engage the projection 60 on the outside surface of the flap 36<SP>1</SP>a which is thereby caused to swing inwardly about its pivotal connection with the duct 36. The flaps 36<SP>1</SP>b are caused to move simultaneously with the flaps 36<SP>1</SP>a by means of retainer elements 35. The discharge opening of the nozzle is arranged to be approximately the same area whether the divider elements 246 are extended or retracted.