GB900603A - Gas turbine engine - Google Patents

Abstract

900,603. Gas turbine jet propulsion engines. ROLLS-ROYCE Ltd. May 1, 1961 [May 6, 1960], No. 16196/60. Class 110 (3). [Also in Group XXXIII] A by-pass gas turbine having mixing means by which the by-pass air is mixed with the jet gases prior to their exit through the propulsion nozzle, has valve mechanism associated with the mixing means operable selectively to divert at least a proportion of the by-pass air into an ancillary air conduit, and being so designed as to ensure that by-pass air is always mixed with the jet gases. A gas turbine by-pass engine has an annular by-pass passage 15 arranged to receive compressed air from the outlet of the lowpressure compressor (not shown). The downstream end of the passage 15 extends into the jet pipe 16 downstream of a diffuser cone 17. The passage 15 also communicates by way of apertures 20 with a series of angularly-spacedapart conduits 21 leading to a volute 22. Each aperture 20 is opened and closed by a flap valve 24 which valves are interconnected for movement in unison. When the flap valves are in the full line position shown they extend into the bypass passage 15 and restrict the flow to the spaces between themselves. In this position a part of the by-pass air is supplied to the volute 22 and a reduced amount to the jet pipe 16. In the dotted line position shown, the flap valves prevent any flow of by-pass air to the volute 22. The volutes 22 of a number of engines are connected through ducts to vertical nozzles at the fore and aft ends of the aircraft fuselage. Means may be provided to alter the relative amounts supplied to these vertical nozzles. A part-cylindrical deflector 34 is mounted on a fluid shaft 34<SP>1</SP>. The shaft 34<SP>1</SP> also supports a freely-rotatable cam 35 which engages a flap 36 forming part of a variable-area nozzle. An hydraulic or pneumatic ram 38<SP>1</SP> pivots the jet deflector 34. A further hydraulic or pneumatic ram 40 has rods 42, 43 which are connected to the flap valves 24 and the cam 35 respectively. At take-off the ram 40 is operated to place the flap valves 24 and the flap 36 into the full-line position shown and the ram 38<SP>1</SP> moves the deflector 34 into the broken line position. The flap-valves 24 allow some of the bypass air to pass to the volute 22 and the flap 36 is in its minimum area position. When the aircraft reaches a predetermined speed during take-off, the ram 38<SP>1</SP> is operated to move the jet deflector into the full-line position and so deflect the jet gases downwardly. When the aircraft is airborne, the ram 38<SP>1</SP> is actuated to return the jet deflector 34 to the broken-line position and then the ram 40 is actuated to move the cam 35 into the broken-line position where the flap 36 is in the maximum area position and the flap valves 24 are moved to seal the apertures 20. The flap 36 may be dispensed with by making the jet deflector such that its outlet area is reduced when it is deflecting the gases downwardly. In a modification, Fig. 4 (not shown), a rotatable annular valve member replaces the flap 24.