GB760631A - Improvements in or relating to gas turbine power plants - Google Patents

Abstract

760,631. Gas turbine plant; Jet propulsion plant. SHEPHERD, G. R. (Westinghouse Electric International Co.). May 26, 1954, No. 15493/54. Claes 110(3). [Also in Group XXIX] A system for controlling the fuel supply to a jet propulsion gas turbine engine 10 during acceleration so as to avoid stalling of the compressor or overheating of the engine comprises an acceleration control valve 47 arranged in the fuel supply pipe between the pump 25 and the combustion apparatus 13 and controlled by a pressure-responsive element such as the evacuated bellows 56, which may be subjected alternatively to the compressor inlet pressure through a pipe 60a or the compressor outlet pressure through a pipe 60b, the change from one pressure to the other being effected by a changeover valve 65 which is opened automatically to expose the pressure-responsive element to the compressor delivery pressure when the engine speed exceeds a predetermined value. An hydraulic actuator 19 for the variable area exhaust nozzle 17 of the engine is operated simultaneously with the change-over valve 65, the nozzle area being reduced to its minimum value when the change-over valve is open. The change-over valve 65 is closed by the energization of a coil 66 in circuit with a coil 20 controlling the actuator 19 and a switch 102, 103 controlled by the speed-responsive mechanism 29. The latter comprises a ported sleeve 76 driven from the engine and within the sleeve a piston valve element 77 position by centrifugal weights 75. The valve element 77 controls the admission pressurised fuel through a control pressure pipe 84 to a piston 91 connected to the movable element 103 of the switch and to an overspeed valve 36 in the fuel supply. At high speeds the pipe 84 is vented through a port 85 and a pipe 43. The valve 36 is arranged in a throttle device 31 also containing a throttle valve 37 having a metering port 40 and a bypass port 42. The valve 37 is operated by an element 38. The acceleration control valve 47 is of the double-seated type and is operated against a spring 53 by a stem 58 connected to the bellows 56. Under the influence of compressor inlet pressure some of the fuel is diverted past the lower valve seat 48 and a passage 49 to the return pipe 43 but when the changeover valve 65 is open, the compressor delivery pressure contracts the bellows 56 and the valve 47 closes on its lower seat 48 so as to allow the fuel to pass entirely to the combustion apparatus 13.