904,138. Turbine stator casings. BRISTOL SIDDELEY ENGINES Ltd. Jan. 22, 1960 [Jan. 23, 1959], No. 2632/59. Class 110 (3). A casing forming part of the stator structure of a rotary machine having an annular fluid flow passage, for example an axial-flow gas turbine, comprises an outer wall and an inner annular wall part which defines the outer wall of the annular fluid flow passage. The outer wall has inwardly projecting parts which radially overlap outwardly projecting parts of the inner annular wall part and axially projecting pins are mounted in the projecting parts of one of the wall parts and engage in radially extending slots in the projecting parts of the other of the wall parts so that the inner wall part is supported from the outer wall by the pins. A three-stage axial-flow gas turbine is shown and comprises three rows of stator blades 10 and three rows of rotor blades 11, also a stator structure comprising an outer wall 14 made up of an upstream section 15 bolted to a downstream section 16 and an inner wall 13 which forms the outer boundary of the working fluid passage and which is made up of the outer wall 20 of the turbine inlet duct 18, a first-stage shroud ring 21, an annulus of second-stage stator blade platforms 22, a second-stage shroud ring 23 and an annulus of third-stage stator blade platforms 24. The outer wall section 15 is formed with an inwardly-projecting radial flange 25 and with two axially-spaced rows of circumferentially-spaced, iuwardly-projecting lugs 26, 27, the flange and lugs being formed with axially-extending holes 31, 35 and 44 respectively. The inlet duct wall 20 is formed with a radial flange 28 which is formed with openended slots 30. Locating pins 32 are secured in the holes 31 in the flange 25 by means of split pins passed through holes 34 in the shanks of the pins and the flat-sided heads 33 of the pins engage in the slots 30 whereby the duct wall 20 is supported from the flange 25. The rotor blade shroud 21 is formed at its downstream end with a flange 37 which is disposed adjacent the downstream face of the lugs 26. Pins 36 are engaged in the holes 35 in the lugs 26 and the flat-sided heads 42 of the pins engage in open-ended recesses 39 formed in the radial flange 37 by means of pairs of radial projections 38. The platforms 22 of the second stage stator blades 10 are formed at their upstream ends with radial flanges 40 which abut against the flange 37 of the shroud 21 and prevent disengagement of the pins 36. The flanges 40 are also formed with pairs of upstream-projecting shoulders 41 which define recesses which engage with the pairs of radial shoulders 38 formed on the flange 37. In this way the shroud 21 and the stator blade platforms 22 are supported from the outer wall 15. The shroud 23 for the second stage rotor blades is also formed with a radial flange 46 which abuts against the supporting lugs 27, and open-ended slots 48 are formed in the flange. Pins 45 having flat-sided heads 51 engage in the holes 44 in the lugs 27 and the ends of the pins, which are formed with flats 53 engage in the recesses 48 formed in the flange 46. The platforms 24 of the third-stage stator blades 10 are formed at their upstream ends with radial flanges 49 and at their downstream ends with radial flanges 54. The flanges 49 are formed with pairs of circumferentially-spaced shoulders 50 which extend axially upstream so as to form recesses which receive the flat-sided heads 51 of the pins 45. A step 55 in the outer wall section 16 abuts against the downstream radial flanges 54 of the blade platforms 24. The wall sections 15, 16 are bolted together, the outer wall section 15 being secured by welding at its upstream end to the adjacent wall of the combustion equipment, and wall section 16 being welded at its downstream end to the turbine exhaust duct 19.
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