Patent GB-1284287-A (GB)
Title: A device for programming the ignition stage of the re-heat combustion in a gas turbine power plant
Inventor: TISSIER ROGER HENRI
IPC: F02K3/10
Filed: 1969-10-07
Abstract: 1284287 Jet propulsion engines SOC NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIATION 7 Oct 1969 [10 Oct 1968 15 Sept 1969] 49192/69 Heading F1J Branch pipe means by-passing the reheat metering device can be closed by a shut-off device including a movable valve element, a movable body mechanically connected for movement with the valve element, the movable body being subjected in one direction to the action of the fuel pressure prevailing in a selected portion of the branch pipe means and in the other direction to the action of a restoring force, the movable body being movable to cause the valve element to close the branch pipe means when the pressure exceeds a value predetermined by the restoring force, and means whereby an ignition device is rendered operable by the movement of the movable body. Fuel is fed from a pump 8, Fig.2, to reheat injection manifolds R1 (and R2, R3, not shown) via a metering device 11 which meters the fuel-flow in accordance with variables of the engine and/or the atmosphere. During operation without reheat, compressed air is supplied via a pipe 16 to sweep fuel out of the reheat injection manifolds R1, R2, R3 and their supply pipes CR1, CR2, CR3. When the pump 8 is started to initiate reheat, a valve 13 operated by the fuel pressure closes the connection to the pipe 16 and opens a connection to the fuel pipe 12. Initially, the flow through the metering device 11 is supplemented by a high flow via a by-pass circuit 18, 19, whereby the injectors and their supply pipes are rapidly re-filled with fuel. When they are full, the resultant rise in pressure in the pipe 18 causes the piston 26b of a device 26 to move to the right in opposition to the force of a spring 26c, thereby closing valve ports 26baa to terminate the flow through the by-pass circuit. The fuel-flow is now under the control of the metering device 11. A valve port 26ag through which the fuel pressure in a chamber 26ad is relieved to the inlet side of the pump 8 is closed at the same time as the ports 26baa. The subsequent movement of the piston 26b forces fuel from the chamber 26ad through a line 22 to an auxiliary injector 17 opening into the main combustion chamber of the engine, whereby a torque of flame from the auxiliary injector is projected through the turbine blades to ignite the reheat fuel. When the pump 8 is stopped to terminate the reheat, the piston 26b returns to its initial position, thereby drawing fuel into the chamber 26ad via a non-return valve 23 in readiness for the next operation. In a modification, Fig.5 (not shown), the spring (126c) is located outside the chamber (126ad) and surrounds the piston (126b). The device 26 shown in Fig.2 may be used in connection with the injection manifold R1 and the igniter 17, while simplified devices which only ensure the accelerated pre-filling of the injection manifolds may be used for the remaining injection manifolds. Fig.7 shows an embodiment in which the device 226 controls the by-pass circuit 18, 19 as in the previous embodiments but controls the operation of the ignition injector 217 electrically. For this purpose, a contactor 30 closes an electrical circuit to open an electricallyoperated valve 38 to feed fuel to the ignition injector 217. Alternatively, an electric igniter 31 of the spark or incondescent filament type may be operated. The ignition operation is terminated by a time switch 33 or an ignition detector 35. The device 626 shown in Fig.12 differs from the device 26 of Fig.2 mainly in that a comparitively weak spring 626j is ued, the force opposing movement of the piston 626d being in this case mainly provided by a hydraulic force exerted upon an auxiliary piston 626k which is subjected via a pipe 58 to the delively pressure of the pump 8. As before, an ignition injector (17) is supplied via a pipe 22, but in addition a relay ignition injector located between the ignition injector and the reheat injection manifolds and functioning to extend the torque of flame initiated by the ignition injector may be supplied with fuel via a port 626de which is closed at the end of the stroke of the piston 626d. The auxiliary piston 626k may be replaced by an annular piston (426dl), Fig.10 (not shown), carried by the main piston. In further modifications, Figs.14, 15, 16 (not shown), the hydraulic force opposing movement of the main piston is provided by a fuel pressure which is intermediate the delivery pressure of the reheat fuel pump 8 and the delivery pressure of the main fuel pump of the engine, this intermediate pressure being obtained by a fuel potentiometer consisting of a pair of restrictors connected between the delivery sides of the two pumps.