Patent GB-832641-A (GB)
Title: Jet propulsion power plant
Inventor: HOWELL ALUN RAYMOND
IPC: F02C3/067
Filed: 1956-12-28
Abstract: 832,641. Gas turbine jet propulsion engines. POWER JETS (RESEARCH & DEVELOPMENT) Ltd. Dec. 24, 1957 [Dec. 28, 1956], No. 39414/56. Class 110 (3). A gas turbine jet propulsion power plant of the by-pass type having a by-pass compressor, a high-pressure compressor, a combustion system and a turbine arranged in series flow relationship successively from front to rear of the plant comprises a turbine including two mechanically independent turbine rotors in driving connection, one with each of the compressor rotors through coaxial shafts one within the other, the turbine rotor in driving connection with the by-pass compressor rotor carrying a row of turbine rotor blades which are upstream of, in guide blade relationship with and contra-rotate with respect to a row of turbine rotor blades carried by the other turbine rotor. The gas turbine plant comprises an outer casing 1 having an air inlet 2 and jet nozzle 3 in which is supported a cylindrical shell 4 by struts 5 to define a by-pass duct 6. The shell 4 encloses a high pressure compressor 7 supplying air to an annular combustion chamber 14 discharging through the turbine inlet nozzle vanes 17. The turbine comprises a rotor disc 18 and a second rotor comprising two rotor discs 20, 21 which contra-rotate with respect to the disc 18. The rotor blades 22, 23 are drivingly connected by a shroud 24 which may be fixed to the blades 22 and connected to the blades 23 by means which transmits torque but allows the blades to expand radially. The blades 22, 19 are in guide blade relationship to the blades 19, 23 respectively, i.e. one set of blades discharges directly on to the other set and no intervening turbine stator blade rows are provided. The disc 18 drives the compressor 7 through the shaft 29. The discs 20, 21 drive the by-pass compressor through a shaft 31. The by-pass compressor comprises a rotor 38 carrying two rows of rotor blades 39 which co-operate with stator blades 47, 40, 35. The turbine blades 22, 23 are designed to rotate at about half the speed of the blades 19. A mixer 50 is provided to mix the turbine exhaust gas stream and the by-pass air stream. The shell 4 may be extended to the nozzle 3 and the exhaust gas and air stream discharged separately. The turbine stator blades 17 may be dispensed with. The plant may be controlled by adjusting the angular position of the blades, preferably the stator blades of the by-pass compressor and of the early stages of the high-pressure compressor. A clutch or brake may be provided to hold the by-pass compressor rotor 38 stationary whilst starting and possibly during idling. At high Mach. numbers, the plant may be operated as a ram jet, in which case the fuel supply to the combustion chamber 14 is discontinued and the high pressure compressor and turbine allowed to come to rest. The provision of a clutch or free wheel device in the coupling 49 will allow the by-pass rotor to windmill or alternatively the blades 35, 39, 40 may be feathered so that the rotor 38 also comes to rest. In a modification an additional compressor is provided within the shell 4. Specification 819,032 is referred to.