GB879444A - Improvements in two-tier turbine and compressor blades - Google Patents

Abstract

879,444. Two-tier turbine and compressor blades. GENERAL ELECTRIC CO. Sept. 3, 1959 [Sept. 5, 1958], No. 30098/59. Class 110 (3). In a rotor assembly for a turbine driven ducted fan thrust augmentor in which the secondary air duct is separated from the turbine exhaust duct by an intermediate wall 12, a plurality of two-tier blades 23 is mounted at the rotor periphery, each blade comprising an inner turbine blade 24 and an outer fan blade 25, a platform portion 26 being disposed therebetween. Interengaging faces are formed on the adjacent lateral faces of the platforms and serve to resist torsion and centrifugal twisting forces. The abutting lateral surfaces of the platforms are formed with at least one pocket for receiving sealing means which prevent leakage from the turbine exhaust duct into the secondary air duct. The thrust augmentor shown in Fig. 1 comprises a rotor disc 18 connected to stub shafts 19, 20 which are supported in bearings 21, 22, which are in turn supported from the inner wall 13 of the exhaust gas duct. The air passage is defined by an outer wall 11 and an intermediate wall 12, and the turbine exhaust passage by the intermediate wall 12 and the inner wall 13, the walls being secured together by struts 14, 15. Turbine inlet nozzle guide vanes are provided at 16 and fan outlet blades at 17. Teeth 27, 28 are formed on the upstream and downstream faces of the platforms 26 and co-operate with adjacent stationary structure to provide seals between the exhaust gas duct and the air passage. The circumferentially-facing surfaces of the platforms 26 are recessed at 36, 37 and one surface is provided with a recess 31 and the other with a projection 32, the projection 32 on one platform interengaging with a recess 31 on the adjacent platform, the axially-facing surfaces 44, 45 of the projection 32 and recess 31 respectively also abutting against each other. Sealing members 38, as shown in Fig. 4, are engaged in the adjacent recesses 36, 37 of adjacent blades, the sealing members comprising a central portion 39 with downturned ends and with downwardly and reverselyturned arms 40, 41, 42, 43, the arms resiliently engaging in the recesses 36, 37 and the central portion 39 affording a seal between the abutting faces of the platforms. In a further embodiment, the platforms are each formed with two recesses in each circumferentially-facing surface thereof, four sealing members being associated with each platform. The interengaging recess and projection are formed at downstream halves of the platforms, the interengaging axially-facing surfaces lying in the central transverse plane of the platforms.