GB1270959A - Means for cooling or regulating the temperature of a gas turbine engine - Google Patents

Abstract

1,270,959. Gas turbine engines - cooling. BENNES MARREL. July 31, 1969 [Sept. 27, 1968], No. 38483/69. Heading F1G. The invention relates to a gas turbine engine of the kind having compressor, combustion equipment, a first turbine driving the compressor, and a second turbine which drives a power output shaft, there being means to cool parts of the engine comprising three systems, firstly one utilizing air taken from the compressor, secondly one utilizing air taken from the chamber into which the compressor discharges high-pressure air, and thirdly one utilizing air drawn in from atmosphere. The engine shown comprises a centrifugal compressor 2 mounted on shaft 1 and driven by HP turbine 3, and a separate LP turbine 5 mounted on a shaft 6. The compressor discharges air to annular chamber 9 from which the air passes to two combustion chambers (not shown), the gases passing to an annular chamber 10 from which they are directed by inlet guide vane assembly 38 on to the HP turbine. Gases from the HP turbine are re-directed by interstage guide vane assembly 11 on to the LP turbine 5, the gases finally discharging through exhaust duct 12. The shaft 1 is supported in a bearing 4 and the shaft 6 in a bearing 7. Air is taken from the discharge of the compressor 2 as indicated by arrow 15 and passes through seal 17, then in part through seal 19 to chamber 13 then through seal 22 to chamber 24 of bearing 4. A second part of air from seal 17 passes through duct 20 arrow (41), Fig. 5 (not shown), to the seal 21, one part flowing through seal 21 to chamber 14 as indicated by arrow (42), the air then passing through seal 23 to chamber 34 of bearing 4. The chambers 24, 34 communicate through ducts (35), 36, 37 with atmosphere so as to permit a through-flow of cooling air. The chambers 13, 14 are interconnected by duct 26 through which a portion of air flows from the chambers 13, 14 through duct 27 to chamber 29 as indicated by arrow 28 on Fig. 1. From chamber 29 the air flows within the wall of the exhaust duct 12 as indicated by arrows 30, some finally discharging through orifices 76, some discharging through openings 75 into the exhaust gas stream and some passing through openings 31, 32, see Figs. 1 and 7, to cool the downstream face of the LP turbine rotor disc 5. A portion of air from the duct 20 flows through the seal 21, Fig. 5 (not shown) to cool the upstream face (40) of the HP turbine rotor disc 3 as indicated by arrows (43), (45). A portion of hot gases is taken from the chamber 10 upstream of the inlet guide vane assembly 38 through ducts (39) to control the temperature of the cooling air (43) flowing past the upstream face (40) of the HP turbine rotor disc. Air from the chamber 9 is also passed through ducts (77) for the same purpose. The above comprises the first cooling system. In the second cooling system, HP air is taken from the annular chamber 9 through ducts 46, 47, Figs. 1 and 2 to the annular manifold 48 of the interstage guide vane assembly 11, the air then passing through hollow struts 49 to the inner annular space 50. An interstage diaphragm 52 is secured to the inner wall of the space 50 and openings 53, 54 are formed in the inner wall at each side of the diaphragm whereby cooling air flows into the spaces 55, 56 adjacent the downstream face of the HP turbine rotor disc 3 and the upstream face of the LP turbine rotor disc 5 respectively. The air flows from the spaces 55, 56 into the turbine working fluid stream as indicated by the flow arrows 57, 58 and 59, 60 respectively. In the third cooling system air is drawn into chamber 65 through openings 66 as indicated by arrows 74, passing to a chamber 67, see Fig. 7. One portion of air from chamber 67 is drawn by a screw pump device 70 on the shaft 6 and flows as indicated by arrow 71 to cool the shaft bearing indicated at 7. A second portion of air from the chamber 67 is drawn by a centrifugal pump device comprising a series of radial grooves (78) and flows as indicated by arrow 72 through seal 73 to flow together with air-flow 30 across the downstream face of the LP turbine rotor disc 5.