GB1142862A - Improvements relating to the starting of gas turbine engines - Google Patents

Abstract

1,142,862. Gas turbine engines - starting. PLESSEY CO. Ltd. May 27, 1966 [May 28, 1965], No.22896/65. Heading F1G. The invention relates to a method of starting gas turbine engines in which a jet of gas under pressure is caused to impinge upon the blades of the turbine so as to bring the turbine up to sufficient speed to permit further operation of the turbine in the normal manner after ignition of a fuel and air mixture. In accordance with the invention the jet of gas under pressure is obtained by the decomposition of a monofuel under pressure. The invention is described with reference to the starting of a series of gas turbine lift engines 1, 2, 3, 4, 5, the starting gases passing from a monofuel decomposition chamber 7 to a manifold 6 and thence to starting nozzles 1a, 1b 2a, 2b &c. directed on to the turbine blades of the gas turbine engines. Monofuel such as isopropyl nitrate is supplied from tank 8 by pump 9 through shut-off valve 11 to the chamber 7. To initiate the operation a cartridge contained in breech 14 is fired, the resulting gases passing in part through line 17 to a turbine 12 which drives the monofuel pump 9, and in part through line 18 to the decomposition chamber 7 which is thus brought to a pressure and temperature suitable for decomposition of the monofuel which is supplied thereto once the valve 11 is opened. The decomposition gases then pass to the starter nozzles 1a, 1b, 2a, 2b &c., a portion of the gases passing through line 13 so that the turbine 12 continues in operation. The turbine engines are brought to overspeed before the supply of decomposition gases is shut off so that the gases are discharged from the turbines before the gases from the engine combustion equipments reach the turbines so as to prevent combustion of the decomposition gases in the turbines. The starting nozzles are inclined to the blade velocity vector at a more acute angle than the main inlet nozzles of the gas turbine as indicated in Fig. 2.