Patent GB-884588-A (GB)
Title: Jet propulsion nozzle
Inventor: WORSHAM JAMES EVERETT
IPC: F02K1/12
Filed: 1958-04-18
Abstract: 884,588. Jet propulsion plant. GENERAL ELECTRIC CO. April 18, 1958, No. 12453/58. Class 110 (3). [Also in Group XXV] An exhaust nozzle for a jet propulsion engine comprises a main cylindrical flow passage, a radially displaced outer concentric shroud, an inner variable area nozzle provided by a plurality of flaps pivotally supported at the downstream end of the main passage and a second, outer, variable area nozzle provided by a plurality of flaps pivoted on a ring member which is axially slidable and in sealing arrangement with the shroud, the nozzles being interconnected so that axial movement of the second nozzle produces a variation of the areas of both nozzles in the same sense, as well as a variation in the axial spacing, increased spacing being concomitant with increased area. The inner nozzle forms an adjustable converging portion of the jet pipe nozzle while secondary air flowing or pumped through the annular passage between the nozzles forms an aerodynamic wall defining the divergent portion of that jet pipe nozzle. This divergent portion is varied by the relative movements of the two nozzles. The inner nozzle comprises a number of peripherally spaced flaps pivotally connected at 18 to the downstream end of the tail pipe 11. Floating plates 21 (see Fig. 4) overlap the inner surfaces of the flaps sufficiently to ensure sealing between the flaps irrespective of the angular position of the latter. The plates are held against the flaps by the gas pressure during engine operation, retaining clips 24 being also provided. The inner faces of the flaps 15 are cooled by directing gas, at approximately turbine exit temperature, through the annular orifice 25, formed by the liner 12 and the tail pipe 11, and over the inner faces of the flaps. Louvres may be provided in the liner to achieve the same purpose. The second nozzle is formed by hollow sheet flaps 14 arranged peripherally around the downstream end of a ring 34 slidably mounted within a shroud 10 disposed concentrically with the tail pipe. Sealing means 29 are provided between the adjacent edges of the flaps and the ring 34, while floating plates 26, each slidable within a pair of adjacent hollow flaps, form seals between the flaps. The flaps 14 and 15 are provided in corresponding numbers. Each flap 15 has a bracket 22 which carries a pin 47 slidable within a cam slot 46 in a lever 44 which is itself pivoted at one end to a bracket 45 fixed to the shroud 10. The other end of the lever is pivotally connected to the end of one arm of a bell crank lever 38 pivoted at 39 to a bracket 35 carried on the slidable ring 34, the end of the other arm being pivotally connected at 40 to an extension of a rib 30 integral with the flap 14. A pin 42 on the rib 30 is slidingly pivoted in a slot 41 in the bracket 35. As the ring 34 is moved axially of the shroud 10 in a downstream direction by a control rod 36 the flap 15 and the cam lever 44 move anticlockwise, rocking the bell crank lever 38 clockwise and hence causing the flap 14 to open anticlockwise. Specification 884,587 is referred to.