GB743859A - Improvements in or relating to fuel systems for gas-turbine engines - Google Patents

Abstract

743,859. Gas turbine plant. ROLLS-ROYCE, Ltd. Feb. 22, 1954 [Feb. 27, 1953], No, 5645/53 Class 110(3) In a fuel system for a gas turbine engine, a centrifugal pump delivers fuel to fuel injectors in combustion equipment connected between a compressor and a turbine, the centrifugal pump being driven by an air motor which is supplied with air compressed by the compressor, and an engine-driven positive-displacement pump delivers fuel to the same combustion space as the centrifugal pump. In the jet-propulsion engine shown, a cetrifugai pump 18 and a gear pump 25 draw fuel from, preferably, the same source, such as a tank 21 by way, it may be, of a booster pump 22. The pumps discharge to a manifold 23 supplying fuel injectors 12. Pump 18, which may have a single-sided impeller as described in Specification 709.002, is driven by an air turbine 31, which receives air through a pipe 34 from the discharge 32 of the compressor 10 of the engine or, as shown at 134, from an intermediate stage of the compressor or. as shown at 234, from the air casing of the combustion equipment 11. Pump 25 is driven from the engine shaft 17 through a connection 33. Since the pressure of the air supply to the air turbine 31 is, for a given engine speed proportional to the intake pressure of the compressor 10, the pumo 18 is automatically driven at a speed at which its fuel delivery is approximately equal to the engine demand. The gear pump 25, compensates for the too low delivery of the centrifugal pump 18 at low engine speeds, back flow through the pump 18 at low engine speeds from the pump 25 being prevented by a non-return valve 28. Pump 25 has a non-return valve 36 and a relief valve 38 which keeps its pressure constant. Coupled shut-off cocks 39 are provided. A throttle 24 controlling by means 24a which may be as described in Specification 693,429 regulates the supply of fuel to the injectors 12. The throttle may be in the air supply pipe 34 instead. In modifications, the non-return valves are omitted, and the pumps 18 and 25 supply separate fuel injectors. or separate concentric chambers of fuel iniectors, such as those described in Specifications 645,696 and 645,908 [both in Group XI].