GB597261A - Improvements in or relating to prime movers for aeroplanes or the like - Google Patents

Abstract

597,261. Gas turbines ; jet-propulsion of aircraft. LYSHOLM, A. Aug. 22, 1945, No. 21493. Convention date, Sept. 1, 1944. [Classes 110 (i) and 110 (iii)] In controlling the operation of a gas turbine plant for the jet-propulsion of aircraft, with or without an associated airscrew, compressed air is bled from before the combustion chamber, or, between the stages of a multi-stage compressor, and is discharged into the atmosphere through either forwardly or rearwardly-directed nozzles to diminish or augment the propulsive force of the main propulsive jet. Exhaust gases from the turbine, also, may be discharged through forwardly directed nozzles. These controls are associated with fuel regulation and a device for varying the area of the main propulsion jet. In the plant shown in Fig. 1, a multi-stage turbine 27 drives a multi-stage compressor through a speed increasing epicyclic gear 54. The compressor comprises an axial flow stage with fixed blades 12 and running blades 10 and a centrifugal stage with axial entry blades 14 and centrifugal blades 13. Air from the compressor is discharged into a chamber 17 from which it passes through nozzles 22 into a single annular combustion chamber 3. Fuel is admitted through pipes 23. Air from the chamber 17 may be discharged directly to the atmosphere through forwardly directed nozzles 18 or rearwardly directed nozzles 19. The turbine exhaust goes to a propulsion jet 29, the effective area of which can be varied by means of a cone 32 which can be moved axially by means of a screwed spindle 36 and worm-gear 34. Exhaust gases may also be exhausted through openings 47 governed by flap valves 48. The discharge from the volute 15 of the compressor is by way of tangential conduits 16, Fig. 4, which terminate in right-angle turns. Alternating with these conduits, there may be other similar conduits 60 which project through the nacelle of the plan and discharge air to the atmosphere rearwardly. In another plant, the compressor having two centrifugal stages is driven at turbine speed and an airscrew is driven through a speed-reduction epicyclic gear. Flap controlled orifices permit the discharge of air to the atmosphere from the interstage space and frc m the space between the compressor and the combustion chamber either in a forward or a rearward direction. The positions of the controls are given for five working conditions, namely, two stand-by conditions, idling, cruising speed and full speed. Change from one set of positions to another may be effected by one control lever, or, two levers, one for stand-by and one for load conditions. Additional independent adjustments are provided. Slowly cha iging conditions may be met by fuel and air bleed regulation only and to provide for this the propulsion jet area control transmission includes a hydraulic leak device which is effective to transmit only when the movement of the control lever is rapid.