GB886626A - Improvements in or relating to axial flow turbines or compressors - Google Patents

Abstract

886,626. Axial-flow turbine and compressor stator casings. BRISTOL SIDDELEY ENGINES Ltd. Sept. 2, 1959 [Sept. 4, 1958], No. 28434/58. Classes 110 (1) and 110 (3). In a multi-stage axial-flow turbine or compressor, a shroud ring is disposed in the annular space between the tips of rotor blades of each row and the inner surface of the stator casing, each shroud ring having at least one end face in sealing abutment with an annular end face formed by the root portions of the blades of a row of stator blades and the other end face in sealing engagement with an annular abutment. Each shroud ring thus forms a shield between the working fluid passage and the stator casing. Each shroud ring and each annular member supporting a row of stator blades is supported and guided from the stator casing so as to accommodate relative radial expansion and contraction. The turbine shown comprises a first row of stator blades 13, second and third rows of stator blades 7 and three rows of rotor blades 16, all disposed within a stator casing 1, the diameter of which increases in steps in the downstream direction. The stator blades 13 and 7 have circumferentially abutting platforms 17 and dovetail-shaped blade roots, the roots of the blades 13 being received in grooves formed in the stator casing 1, while the roots of the blades 7 are received in grooves in blade-carrying rings 8 which are supported within the stator casing 1 by means of extensions 11 on the rings engaging in annular grooves 12 formed in the stator casing 1. Radial pins 9 extend through the casing 1 to engage in slots 10 formed in the blade-carrying rings. Shroud rings 15 are disposed in the annular spaces between the tips of the first two rows of rotor blades 16 and the stator casing 1, the shroud rings each abutting at each end against the annular surfaces formed by the adjacent blade platforms 17. The second shroud ring 15 is also engaged by the radial pins 9 which project through the casing whereas the first shroud ring 15 is engaged by radial pins 20. The shroud ring 18 disposed around the third row of rotor blades 16 similarly abuts at its upstream end against the adjacent blade platforms 17, but at its downstream end abuts against a ring 19 secured to turbine stationary structure 2. The ring 18 is also engaged by radial pins 9. The second shroud ring 15 and the third shroud ring 18 are formed with annular recesses 21 with which shroud rings secured to the tips of the rotor blades co-operate. The stator casing 1 is secured at its downstream end to stationary structure 2 and engages at its upstream end in an annular groove 5 in the combustion chamber casing 6 which is also supported from the stationary structure 2. Cooling fluid may be circulated through the spaces between the shroud rings and the stator casing.