Patent GB-777352-A (GB)
Title: Improvements in fuel control means for use with a turbojet engine having an afterburner
Inventor: COAR RICHARD JOHN
IPC: F02K3/10
Filed: 1954-06-25
Abstract: 777,352. Gas turbine jet-propulsion plant. UNITED AIRCRAFT CORPORATION..June 25, 1954, No. 18672/54. Class 110 (3). [Also in Group XXVIII] A gas turbine jet-propulsion plant with reheating in the turbine exhaust, in which the reheat fuel is ignited by injecting additional fuel into the main combustion chamber, has the quantity of additional fuel injected through a control comprising a housing having a fuel chamber with an inlet and an outlet, a valve controlling the inlet, means responsive to the fuel pressure in the fuel chamber to close the inlet valve and piston means to displace fuel from the fuel chamber which piston means is controlled by the inlet valve which directs fluid under pressure in the piston means when the valve is closed. The reheat burners in the exhaust pipe of a gas turbine jet-propulsion engine are ignited by injecting additional fuel into a combustion chamber so that a flame passes through the turbine. The supply of additional fuel which is taken from the supply to the reheat burners, is regulated by a control 28. When the fuel supply to the reheat burners is switched on some of the fuel passes through conduit 174, passage 172, groove 158 and passage 176 into the fuel chamber 141. It also passes from the groove 158 through passages 162, 164 and restriction 170 to chamber 166. From chamber 141, the fuel passes through passage 178 into groove 160 which is connected to a drain by a passage 180 having a restriction 184. This permits the chamber 141 to be purged of air. When chamber 141 is filled with fuel, the fuel flowing into chamber 166 urges piston 148 to the left against the action of the spring 150. The piston then cuts off the supply of fuel to the chamber 141 and cuts off passage 180 from the groove 160. At the same time, the compressor discharge pressure from the conduit 115 is connected to a chamber 123 formed between the piston 124 and housing cover 102 through passage 154 and conduit 131 and the fuel discharge conduit 190 is connected to the groove 160. Since the chamber 136 is connected to compressor inlet pressure through conduit 139, the pressure drop across piston 124 forces it to the right, together with the piston 125. The piston 125 shuts off the passage 176 from the fuel chamber 141 and forces the fuel therein through passage 178 and groove 160 into the discharge conduit 190. The piston 125 is held against the piston 124 by a spring 133 which when the piston 125 is in the left-hand position, is at its free length. The initial rate of injection is therefore dependent upon the pressure rise across the compressor which is a function of the air flow. When the fuel supply to the reheat burners is switched off, the spring 150 moves piston 148 to the right and resets the control in the position shown in which it is ready for further actuation. The reheat burner fuel pump is driven by an air turbine supplied with air from the compressor discharge. The fuel supply to the reheat burners is controlled by the turbine exhaust temperature. The air supply is controlled by an electrically-operated valve which is energized together with a fuel tank booster pump, a shut-off valve in the reheat metering control and an amplifier sending signals to the metering control from a common switch. A variable area nozzle controlled by the turbine discharge pressure is also provided.