Patent GB-644719-A (GB)
Title: Method of and apparatus for temporarily increasing the output of propulsive gases from a combustion chamber
IPC: F23R3/26
Filed: 1948-05-14
Abstract: 644,719. Gas turbine plant. NAAMLOOZE VENNOOTSCHAP DE BATAAFSCHE PETROLEUM MAATSCHAPPIJ. May 14, 1948, No. 13284. Convention date, May 14, 1947. [Class 110(iii)] [Also in Group XII] To increase the output of a combustion chamber for a gas turbine plant of the kind in which an air stream is divided during normal operation into primary air which enters the combustion zone and secondary air which mixes with the combustion products leaving the combustion zone, means are provided to pass substantially the whole of said air stream into the combustion zone, to increase the fuel supply to the combustion zone and to add water or other volatile cooling,liquid in such quantity that the temperature of the mixture does not exceed that during normal operation. A combustion chamber for a jet propulsion gas turbine plant, Fig. 1, comprises an outer casing 4, a flame tube 5 and a fuel supply 12. A slide or sleeve valve 6 is arranged around the flame tube 5. In the normal position shown, Fig. 1, the air from the compressor 3 is divided, part flows into the combustion zone through passages near the burner and the remainder flows outside the flame tube to cool it and then passes through orifices 18 to mix with the combustion products. To increase the output of the combustion chamber the slide valve 6 is turned and the interconnecting pipes 24 which pass through helical slots 24<SP>1</SP> cause the valve to move rearwardly. This rearward movement of the valve shuts of the annular space between the flame tube 5 and casing 4 and all the air is forced to flow into the flame tube in the neighbourhood of the burner nozzle. Part of this air passes through orifices 14 which are shut off during normal operation by the ring 15 attached to the valve 6. The rotation of the valve 6 opens the orifices 6<SP>1</SP> and allows part of the combustion gases to pass to one or more jet pipes 9. A balancing piston 11 aids the rearward movement of the valve 6. Operation of the valve 6 is accompanied by an increase of the quantity of fuel supplied and the injection of water into the flame tube from pipes 19 and 20. A modification in which the air flows around the flame tube in the opposite direction to the flow of gases in the flame tube is described. In this arrangement the ports 18 are shut off by the rearward movement of the valve 6. In another modification, Fig. 9, a sleeve 25 is interposed between the flame tube 5 and casing 4. In normal operation, the annular space between this sleeve and the casing 4 is shut off by an annular valve 26 and the dilution air flows between the sleeve and flame tube 5 to the orifices 18. Rearward movement of the valve 6 opens the annular space between the sleeve 25 and casing 4, shuts off the annular space between the sleeve 25 and the flame tube 5 and closes the ports 18 causing part of the air to pass along the outside of the sleeve 25 and back along the outside of the flame tube to the inlet of the flame tube. The valve 6 may be actuated by a rod attached to the valve which engages a helical slot in the casing 4. The gases passing through the orifices 6<SP>1</SP> may actuate a turbine which is formed by the extension of the rotor and stator blades of the main turbine or a separate turbine surrounding the main turbine to the shaft of which it is attached by a one-way clutch. The main turbine may be in two parts, one of which drives an air compressor and the other an airscrew.