Improvements in supersonic convergent-divergent jet exhaust nozzles

• Main Author: RABONE GEORGE ROGER
• Format: Patent
• Language: English
• Published: 12.06.1968
• Subjects: BLASTING; COMBUSTION ENGINES; HEATING; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS; INDEXING SCHEME FOR ASPECTS RELATING TONON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES ORJET-PROPULSION PLANTS; INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUSSUBCLASSES OF CLASSES F01-F04; JET-PROPULSION PLANTS; LIGHTING; MECHANICAL ENGINEERING; WEAPONS

1,116,999. Jet propulsion plant. GENERAL ELECTRIC CO. Aug. 19, 1966 [Dec. 30, 1965], No. 37278/66. Heading F1J. A variable area nozzle for a gas turbine jet propulsion engine includes inner and outer pivoted flaps 28, 32 movable between a convergentdivergent supersonic configuration, Fig. 2, and a subsonic configuration, Fig. 3, by means of the differential fluid-pressure acting across the flaps. In order to reduce the air pressure in cavity 50 bounded by the flaps 28, 32, convergent flaps 20 and a baffle 70 across a by-pass passage 11, air is bled from the engine compressor through a pipe 58 to an ejector pump 52 formed by a nozzle 56 on pipe 58 and a surrounding aspirating tube 54. Such pressure reduction enables the flaps 28, 32 to remain in their subsonic configuration until internal pressure increases to the extent that the flaps move towards their supersonic configuration. A solenoid operated valve 62 controls operation of the pump 52. The secondary air from by-pass passage 11, which may or may not contain a ducted fan, passes as cooling air through passages 20a in flaps 20 to enter the nozzle interior. The adjacent ends of flaps 20, 28, 32 are connected by linkage 42. A spring system may be provided to overcome friction at the flap seals.