Patent GB-856563-A (GB)
Title: System for feeding fuel and additional fluid to gas turbine engines
IPC: F02C3/30
Filed: 1957-12-04
Abstract: 856,563. Gas turbine plant. BENDIX CORPORATION, [formerly BENDIX AVIATION CORPORATION]. Dec. 4, 1957 [Jan. 10, 1957], No. 37818/57. Class 110 (3). [Also in Group XXVIII] A system for feeding fuel and an additional fluid to a gas turbine engine comprises a first conduit for delivering fuel to the engine containing a metering valve and means for controlling the head across the metering valve, a second conduit for supplying the additional fluid to the combustion chamber section of the engine, means for metering the amount of fluid in the second conduit and a device responsive to engine acceleration for controlling the operation of the metering means. The main fuel supply to a gas turbine engine is controlled by a unit 34, Fig. 2, of the type described in Specification 655,311, in which fuel is delivered by a pump 62 into a chamber 64. A by-pass valve 66 maintains the pressure drop across the unit 34 at a desired value. A regulator valve 76 connected to a diaphragm 74 responsive to the pressure drop across the throttle governor valve 88 and to a lever 115 pivoted to a sleeve 114 movable axially by centrifugal weights 113, maintains the pressure drop across the valve 88 proportional to the square of engine speed so that the fuel flow is directly proportional to engine speed. The conduits 56, 58 are connected to a water injection control unit. Fig. 3. To sense an acceleration condition a gear pump 126 is driven from the engine through a shaft 124. Flyweights 128 connected to the shaft urge a spring-loaded balanced piston 130 axially in response to engine speed. During an acceleration, the flyweights 128 push piston 130 to the left causing an increase in pressure in chamber 134. This pressure acts on the balanced piston valve 138 which moves to the left and allows water to be delivered from conduit 144 to conduit 146. A vent 150 defines the rate and duration of the pressure raised in the chamber 134. The rise in pressure in conduit 146 acts on a diaphragm 154 which deflects and opens a fuel shut-off valve between the conduits 56, 58 so that additional fuel, which is proportional to the main flow, is supplied to the engine. A diaphragm 160 subject to the pressure-drop across the auxiliary fuel metering jet 158 opens the valve 166 and allows water to flow from conduit 146 through chamber 168, metering jet 170 and conduit 50 to the engine. The pressure drop across the water metering jet 170 acting on the diaphragm 182 is balanced by the pressure drop across the fuel metering jet 158 acting on the diaphragm 160 and ensures that the water flow is at all times proportional to the fuel flow and are mutually regulated by the throttle opening. In a modification, Fig. 5, the auxiliary fuel and water are delivered to the engine by a pair of reciprocating pumps comprising a water piston 208 and an auxiliary fuel piston 212 connected to a common shaft 210 actuated by a piston 214. Fuel or fluid at high pressure is supplied to a chamber 232, the leak-off from which is controlled by a valve 226. On acceleration, the flyweights 192 move outwards and cause the valve 226 to close the orifice 228. The pressure in the chamber 232 then rises and causes the pistons 208, 212, 214 and shaft 210 to move to the left and feed water and auxiliary fuel to the engine through the check valves 206, 220. The leftward movement of the shaft 210 causes the valve 226 to re-open the orifice 228. The piston 212 is mounted on the shaft 210 in such a manner as to permit slight axial movement which is taken up by a spring 242. This allows the piston 208 to move and apply to the diaphragm 240 pressure which opens the valve 222 before the piston 212 discharges fuel. In another modification, Fig. 7, the pump piston 262 is moved during acceleration by the flyweights 258. In this arrangement the pump pressure in chamber 252 is conveyed through conduit 272 to act on the diaphagm so as to increase the pressure drop maintained across the main governor control-valve.