GB836836A - Method of starting an internal combustion gas turbine engine - Google Patents

Abstract

836,836. Starting gas turbine engines. DE HAVILLAND ENGINE CO. Ltd. Jan. 17, 1958 [July 17, 1957], No. 22692/57. Class 110(3). In a method of starting a gas turbine engine by means of an auxiliary turbine, the auxiliary turbine is actuated by working fluid derived from water and decomposed hydrogen peroxide in such proportions as to maintain the resultant working fluid within a medium temperature range, i.e. within the range between 225‹ C. and 350‹ C. The starter turbine 17 is mounted within a hollow centre body 11 at the inlet end of the engine compressor, the starter turbine shaft 18 driving through epicyclic reduction gearing 19 and a free-wheel coupling 20. The coupling 20 comprises an axially movable sleeve 22 having dog teeth 23 which may engage corresponding teeth on the main compressor rotor shaft 21, the sleeve 22 having an internal quick-pitch screw thread which co-operates with a corresponding thread formed on a spigot driven by the gearing 19. When the starter turbine rotates the inertia of the sleeve 22 causes it to move axially until the dogs 23 engage. Working fluid is supplied to the starter turbine from a catalytic decomposition chamber 32, the chamber being fed with a mixture of hydrogen peroxide and water from a reservoir 30 which is pressurized by air from a cylinder 31. The decomposition products pass through duct 33, an automatic shut-off valve 34, 35 and duct 25 to the starter turbine. The exhaust fluid discharging from the turbine passes through ducts 26 into the engine air intake duct 12. The preferred proportions for the mixture are 73% hydrogen peroxide to 27% water by weight, the water preferably being distilled to remove impurities. Specification 836,835 is referred to.