GB785803A - Arrangement for regulating the flow of after-burning fuel in jet propulsion engines having a two stage combustion system - Google Patents

Abstract

785,803. Jet propulsion gas turbine engines. SOC. NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIATION. June 30, 1955 [July 13, 1954], No. 18954/55. Class 110 (3). The fuel supply to a reheat combustion chamber in the jet pipe of a gas turbine jet propulsion engine is controlled by an automatic device which also regulates the fuel flow to the main combustion chamber in such a manner that the fuel flows to the respective combustion chambers are in a substantially constant ratio to one another. Fuel is supplied to the main burners 3 by an enginedriven gear pump 4 through a regulator 7. The regulator 7 comprises a slide valve 9 which is actuated by a lever 14, the position of which is determined by a centrifugal governor 15 and a detector 16 which is responsive to the pressure difference across the compressor 17 which varies with the temperature of the ambient air. The loading of the governor spring 20 may be varied by the throttle lever 22 to control the engine speed. A second slide 10 is controlled by a diaphragm 13 so as to maintain the pressure drop across the valve 9 constant. The supply of fuel to the burners 3 is arranged to be a linear function of the position of the valve 9. The fuel supply to the reheat burners is controlled by a flow regulator 27 which comprises a slide valve 29 which is positively connected to the slide valve 9 by a rod 30. A diaphragm 31 coupled to a slide valve 32 regulates the pressure drop across the slide valve 29 so that the flow through the valve 29 is a linear function of its position. The pressure difference across the valve 29 may be varied by the throttle lever 22 acting on a biasing spring 33. The slide valve 32 may be replaced by a by-pass valve similar to the valve 11. Shut-off cocks 35, 37 may also be operated by the throttle lever 22. The regulator 16 may also be used to control the flaps 39 varying the area of the propulsion nozzle. In a modification, Fig. 2 (not shown), the slide valve 9 is actuated by a pressure detector and a temperature detector located in a chamber to which a pitot tube and a static tube, responsive to the conditions at the compressor intake, are connected. In this arrangement the loading of the spring 12 is varied by the throttle lever 22 and the loading of the spring 33 may be varied or kept constant. In a further modification, the regulator 27 is dispensed with and the fuel supply to the reheat burners 24 is taken from the conduit 6 supplying the burners 3 through an adjustable needle-valve device. The control of the slide valve 9 is similar to that shown in Fig. 1 except that the biasing spring of the valve 10 is actuated by the throttle lever so that the injection pressure remains the same whether the reheat combustion chamber is in operation or not.