A method of and apparatus for regulating the cross-section of a discharge nozzle

827,897. Jet propulsion nozzles. SOC. NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIATION. June 21, 1957 [July 3, 1956], No. 19676/57. Class 110(3) The area of discharge of a jet propulsion nozzle is varied in part by movable members associated with the outlet of the discharge nozzle and in part by means of auxiliary jets issuing from the movable members. The exhaust nozzle 1, Fig. 2, of a gas turbine jet propulsion engine with reheating in the exhaust pipe, comprises two flaps 2 pivoted about axes 3 parallel and close to a diameter of the discharge nozzle. The flaps are operated by jacks 4 through connecting rods 5. The flaps 2 are provided with slots 7 to which a gas under pressure, for example compressed air from the compressor, is supplied through collectors 8. The gas is supplied through a control valve 11 and conduits 9, 10. For normal working the flaps are placed in the closed position shown and air supplied to the slots 7 to vary the effective area. When the afterburner is operated, the flaps 2 are also opened, thus giving the gases the maximum cross-section of discharge nozzle. The aerodynamic constriction jets may be put into operation in either of the two positions of the flaps 2 or may be applied alone when the flaps are open. In another modification, Fig. 3, having a pair of pivoted flaps 17, a discharge nozzle 13 is provided at the end of the nozzle 1 and further nozzles 22 provided close to the extremities of the flaps 17. The nozzles 13, 22 are separately connected to a source of compressed air through manifold 14, conduit 15 and control valve 16 and manifold 23, flexible connection 24, conduit 25 and control valve 26, respectively. During normal working without reheat, the flaps 17 are set in the closed position. The area of discharge may be varied by controlling the supply of air to the nozzles 22 by the valve 26. This valve may be controlled automatically in accordance with air-speed, altitude and temperature of ambient air. When the reheat is in operation, the flaps 17 arc fully opened and the area available is that of the orifice 12 which may be reduced by supplying air to the nozzle 13. The gases passing out of the nozzle 13 protect the flaps 17 from the action of the hot gases.