GB723546A - Improvements in liquid fuel supply systems for re-heat burners of gas turbine engines - Google Patents

Abstract

723,546. Jet propulsion gas turbine plant. DOWTY EQUIPMENT, Ltd, Feb. 25, 1953 [Dec. 24, 1951], No. 30167/51. Class 110 (3). [Also in Groups XI and XXIX] Apparatus for controlling the supply of liquid fuel to the reheat burners of a gas turbine engine including an engine-driven fixed displacement pump 14 and a servo-operated by-pass valve 20 under the control of a leak-off valve has a branch conduit 38 between the delivery line 16 of the pump 14 supplying the reheat burners and the inlet line of the pump 13 supplying the main burners 12 and valve means 32, 41 are provided at the junction of the branch conduit 38 with the delivery line 16 so that on the operation of manually-operated control means movable into and between " on " and "off" positions, the branch conduit 38 is open and the delivery line beyond the branch conduit is closed when the manual control means are in the "off" position and the branch conduit is closed and the delivery line is open when the manual control means are in the "on" position, means being provided to vent the servo-device of the by-pass valve when the manual control means are in the "off" position. The by-pass 19 across the pump 14 is controlled by a valve 20 operated by a servomotor piston 21 controlled by leak-off valves 46, 52. The servo vent-pipe 25 contains a non-return valve 29 to prevent return flow to the servomotor when the valve 46 is open. The leak-off valve 52 forms part of an automatic regulating device 18 and is carried by a lever 53 loaded by a spring 58 against the fuel pressure in the delivery line 16 acting on a diaphragm piston 55 and a resilient evacuated capsule 59 exposed to atmospheric pressure through a connection 61. The valve means 32, 41 is arranged in a casing 17 and comprises a servooperated piston valve 32 and a piston-type throttle valve 41 operated from the pilot's control lever for the main-fuel supply through a lever 45 and rack-and-pinion mechanism. A finger 51 on the pinion 50 lifts a spring-loaded lever 47 carrying the vent valve 46 when the manual control means are in the " off " position. Opening of the vent valve 46 causes the valve 32 to rise so that the land 34 opens the branch conduit 38 and the land 33 covers a passage 39 leading through an adjustable orifice 40 and a pipe 40a to torch igniter burners of the re-heat system. This corresponds to position A of the lever 45 in which the valve 41 is in its lowest position and cuts off an extension 16b of the delivery line 16 from the line 42 to the re-heat burners and from the outer end of a restricted passage 43 leading to the branch conduit 38. In position B of the lever 45, the vent valve 46 closes and the valve 32 moves down to the position shown. At the same time, the extension 16b remains cut-off from the line 42 but communication starts between the extension 16b and the restricted passage 43. When the pilot's lever moves through a gate to start the re-heat system, the lever 45 moves from B to C and the slots 41a of the valve 41 start to be uncovered. The flow to the torch igniters continues having been started in position B. From lever position C to position D the flow to the re-heat burners increases and the flow to the restricted passage 43 decreases. At position D, the passage 43 is cut off again and-from position D to position E, the fuel flow to the reheat burners progressively increases. Until the vent valve 46 is closed and position B is reached the automatic control device 18 is ineffective.