Patent GB-873969-A (GB)
Title: Improvements in frame structure for turbo-machine having concentric compressor and turbine passages
IPC: F01D25/02
Filed: 1959-11-23
Abstract: 873,969. Gas-turbine jet-propulsion plant; axial-flow compressors. GENERAL ELECTRIC CO. Nov. 23, 1959 [Dec. 30, 1958], No. 39670/59. Classes 110 (1) and 110 (3). In a turbine and compressor assembly comprising inner, intermediate and outer casings defining concentric turbine and compressor passages, the casings are supported by a frame structure which comprises a plurality of concentric, hollow rings secured to the casings and a plurality of hollow struts which extend radially of the casings and are secured to at least two of the rings, the interior of each strut being in communication with the interior of at least one of the attached rings so as to form channels for the circulation of heating fluid through the frame. The invention is shown applied in the case of a turbine-driven ducted fan thrust augmentor which comprises an inner casing 17 and an intermediate casing 16 which define therebetween an annular passage 19 through which exhaust gases from a compressor-turbine assembly 12 flow, turbine rotor blades 24 being disposed in the passage 19; a further annular passage 18 is defined between the intermediate casing 16 and an outer casing 15, a set of compressor rotor blades, supported at the tips of the turbine blades 24, being disposed in the passage 18 and constituting a ducted fan compressor. The front frame comprises an inner ring 25 secured to the inner casing 17, an intermediate ring 26 secured to the intermediate casing 16 and an outer ring 27 secured to the outer casing, the three rings being joined by a plurality of hollow radial struts 28. The rear frame includes an inner ring 29 secured to the inner casing and an outer ring 31 secured to the outer casing, the two rings being joined by radial struts 32. The forward struts 28 are provided with partitions 35, 36 which divide the interior into three passageways 37, 38, 39, cooling air being parsed through the centre passageway 38 and hot turbine gases tapped off through outlet 71 being passed through the leading and trailing passageways 37 and 39. The rearward struts 32 are also hollow and the outer portions thereof are also provided with partitions 57, 58 so as to afford passageways 59, 61 adjacent the leading and trailing edges, gases being tapped from the turbine passage 19 through outlets 74 being led through the passageways 59, 61 and finally discharging to atmosphere. The intermediate ring 26 of the forward frame comprises a pair of U-section annular channels 43, 44 interconnected by a central passage 45, turbine gases being led from outlet 71 into the spaces within channels 43, 44, and thence through openings 46, 47 into the channels 37, 39 within the struts. The outer ring 27 of the forward frame also comprises two U-section annular channels 48, 49 and a central annular channel 53, gases from the channels 37, 39 entering the channels 48, 49 finally discharging to atmosphere. Cooling air from the central channel 38 enters the central annular channel 53 and discharges from there to atmosphere. The portions of the struts 28 disposed within the turbine passage 19 are enclosed within fairings 33 to prevent the hot gases from coming into contact therewith. The outer ring 31 of the rear frame also comprises two U-section annular channels 62, 63 and turbine gases flowing through the channels 59, 61 in the struts 32 enter the channels 62, 63 through openings 67, 68. The gases are finally discharged to atmosphere. The portions of the struts 32 disposed within the turbine passage 19 are also enclosed within struts 34. The object of the invention is to subject the front and rear frame structures to uniform temperatures so that the frames tend to expand uniformly so avoiding stressing due to differential expansion. The passage of the hot gases through the struts also serves to prevent formation of ice.