GB730573A - Improvements in jet propulsion units - Google Patents

Abstract

730,573. Jet propulsion plant. SOC. NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIATION. April 4. 1952 [May 30, 1951], No. 8720/52. Class 110 (3). A jet propulsion unit comprising a duct to which combustion gas is continuously supplied such as jet and propeller turbine engines, ram jets and rockets, has at least two jet nozzles each having an inlet opening adjacent the duct and means associated with the duct in the vicinity of the inlet openings to cause the combustion gas to flow successively toward the inlet openings and into the respective nozzles. The exhaust duct 1, Fig. 1, of a gas turbine jet propulsion engine leads to a propulsion nozzle having a central nozzle 7a and an annular peripheral nozzle 6a, the areas of which are equal. The inlet 8 of the duct 7 is greater than the throat of the duct 1 so that when the deflector device described below is not operating, the flow through the nozzle 7a is unobstructed. The deflector comprises a hollow tapered member 9 having a slot 10 extending over its periphery to which compressed air from any suitable source such as an intermediate stage of the compressor 3 is supplied through a conduit 12 fitted with a control cock 14. The control member 15 is driven continuously by a motor (not shown). In one position of the member 15 air is not supplied to the member 9 and the working fluid flows through the inlet 8 through the nozzle 7a, When the member 15 has turned through 90 degrees, air is admitted to the slot 10 in the member 9 and the gas flow is deflected through the nozzle 6a as shown by the arrows in the upper half of Fig. 1. An annular grid of vanes 17 evens the flow into the nozzle 6a. Pipes 18 leading from the atmosphere to the inner duct prevent back flow of hot gases from the annular nozzle 6a into the inner duct through the nozzle 7a. The increase in area of the ducts between the inlets and the nozzles 6a and 7a are preferably the same. In a modification, the two nozzles are arranged side-byside and in this arrangement, the flow to the nozzles may be controlled by compressed air jets or by rotary baffles. In another modification, provision is made to supply atmospheric air to the ducts leading to the nozzles between pulses of working fluid. In another arrangement, Fig. 8, the working fluid from the duct 1 passes into a distributer 28 which is rotated by a motor 31, so that as the distributer 28 rotates, working fluid is supplied to the nozzles 6a, 6b, 6c ... which are arranged in a circle. The distributer 28 may be arranged so that it discharges the working fluid with a tangential component, in which case the motor 31 may be dispensed with.