GB809793A - Gas turbine plant - Google Patents

Abstract

809,793. Gas turbine jet propulsion plant. POWER JETS (RESEARCH & DEVELOPMENT) Ltd. Feb. 21, 1957 [Feb. 27, 1956], No. 6071/56. Class 110 (3). The invention relates to a particular arrangement of ducted fan gas turbine jet propulsion engine of the kind having three coaxial turbine discs carrying rows of turbine blades through which the working fluid flows in series, the intermediate turbine disc being connected through a shaft to the compressor and the other two turbine discs which are rotatable independently of the intermediate disc carrying at their periphery ducted fan blades. A multi-stage axial flow compressor delivers air to a combustion system, comprising an annular air casing 3 enclosing an annular flame tube 4, feeding an axial flow turbine assembly having three rotor discs 5, 6, 7. The rotor discs 5, 7 contrarotate with respect to the rotor disc 6 which drives the compressor through a shaft 8. The turbine rotor discs 5, 7 carry on the tips of their blades 5a, 7a rows of axial flow ducted fan rotor blades 10, 11, operating in a passage formed by an outer wall 12 which also carries ducted fan stator blades 14. The driving shaft 8 extends beyond the rearward end of a backbone member 9 and carries the rotor disc 6 by a sleeve 22. The rotor disc 5 is mounted by means of a sleeve 23 on a stub shaft 24 supported in the member 9 by roller and ballbearings 25, 26. A roller bearing 27 is mounted between the shafts 8, 24. The rotor disc 7 is attached to a stub shaft 28 supported by bearings 30, 31 in a stationary sleeve 29. The sleeve 29 is supported from the outer structure of the plant by means of the struts 13, 17, 19, 21 and the walls 12, 15, 16, 18. The blades 5a have shrouds 5b carrying axially-extending fir tree roots 5c which engage the roots 10a of the ducted fan blades 10. The blades 11 are similarly mounted on the turbine blades 7a. Anglerings 33, 34 attached by bolts to the ducted fan blade roots extend across the tips of the turbine rotor blades 6a and carry seals engaging the shrouds 14a of the stator blades 14. The rings 33, 34 are formed with interengaging driving dogs 37. Flexible bellows 38 may also be provided to prevent leakage from the turbine. The dogs 37 and bellows allow differential radial expansion of the rotor-discs 5, 7. In some cases, the dogs 37 may be omitted. Sealing rings 39, 40 are provided to prevent leakage of air from the air casing forming part of the ducted fan flow passage. In a modification, Fig. 4 (not shown), the ducted fan rotor blades are attached to the turbine blade shrouds by circumferentially extending fir tree roots. In this arrangement, the rotor discs 5, 7 do not have a positive mechanical connection. A modified form of seal around the turbine blades 6a is also provided.