Patent GB-978658-A (GB)
Title: Gas turbine by-pass engines
Inventor: HEWSON COLIN TAYLOR
IPC: F02K3/06
Filed: 1962-05-31
Abstract: 978,658. Axial-flow fans and compressors; gas turbine jet propulsion plant. ROLLS-ROYCE Ltd. May 10, 1963 [May 31, 1962], No. 21106/62. Headings FIC, F1G and F1J. A gas turbine by-pass engine comprises a high-pressure compressor and a high-pressure turbine each of which has at least one row of rotor blades drivingly engaged with a first shaft, a low-pressure compressor and a lowpressure turbine each of which has at least one row of rotor blades drivingly engaged with a second shaft which is mounted within the first shaft, a by-pass duct which communicates with the downstream end of the low-pressure compressor so as to receive part of the air compressed thereby, a rotatable casing which forms part of the low-pressure compressor and which carries at least one row of rotatable stator blades which are driven by air passing through the low-pressure compressor, and a driven part which requires substantial torque to drive it and which is drivingly connected to the rotatable casing. The aircraft gas turbine by-pass engine shown in Fig. 5 comprises an L.P. compressor 141m and an H.P. compressor 134m driven, through concentric shafts 137m, 132m by an L.P. turbine 131m and an H.P. turbine 130m respectively. The stator blades 142m of the L.P. compressor are carried by a rotatable annular casing 143m which also carries the rotor blades 144m of a fan disposed within fan duct 145m. The air passing through the L.P. compressor rotates the stator blades 142m, and hence also the fan rotor blades 144m, at a speed which may be 30 to 40% of the speed of the rotor blades of the L.P. compressor. A by-pass duct 165m receiving part of the discharge of the L.P. compressor communicates with the jet pipe 207 of the engine via short mixer shoots 208. The fan duct 145m communicates with the jet pipe 207 via short mixer shoots 209 arranged downstream of the mixer shoots 208. A thrust reverser or deflector may be arranged at the end of the jet pipe 207. In alternative embodiments, the by-pass duct does not communicate with the jet pipe, and discharges through an annular orifice concentric with the jet pipe orifice. The fan may be used for. boundary layer suction, for supplying air to vertical-lift fans or to provide altitude control of the aircraft. The fan duct may discharge direct to atmosphere. An intermediate-pressure compressor, driven by the L.P. turbine, may be provided and its stator blading may be rotatable and coupled to the rotatable stator blading of the L.P. compressor. Instead of driving a fan, the rotatable stator blades may drive a propeller, a helicopter rotor, a rudder, an electrical generator or other engine auxiliaries. The drive may be transmitted through a gear box. A brake may be provided for preventing rotation of the rotatable stator blades. The Provisional Specification describes a number of single-shaft embodiments in which the L.P. turbine is omitted. In one such embodiment, the engine can be turned through 90 degrees about trunnions to provide vertical lift. When the engine is used for forward propulsion, a brake is applied to the rotatable stator to put the fan out of action. In another embodiment, L.P. and H.P. compressors are provided. The H.P. compressor rotor is driven by the turbine but the L.P. compressor rotor is driven by the rotatable stator of the H.P. compressor.