GB1230325A - - Google Patents

Abstract

1,230,325. Gas turbine rotor blades - cooling. GENERAL ELECTRIC CO. March 5, 1969, No.11615/69. Heading F1T. The invention relates to means for cooling gas turbine rotor blades by a liquid coolant, each rotor blade having an internal cavity open at the blade tip, there being means for injecting a stream of coolant inwardly through the turbine casing in a direction tangential to the rotor peripheral surface into the path of rotation of the cavity openings. The rotor disc 13, Fig. 1 has a series of blades 11 mounted at the periphery thereof, the rotor being disposed within a stator casing 18. Each blade is formed with a cavity 19 which is open at the tip end and the concave surface of each blade is extended at the tip to form a curved scoop 14, the direction of rotation being clockwise as seen in Fig. 1. A series of injection nozzles 16 are mounted in the casing 18 being arranged to discharge liquid coolant such as water in a direction generally tangential to the rotor peripheral surface. In operation water from the spray nozzle is collected by the scoops 14 and directed radially inwardly into the blade cavities thereby cooling the blades, the water and steam finally discharging from the cavities into the working fluid adjacent the surface of the casing 18. In Fig. 1 the blades are cast or forged whereas in Fig. 3 the blades are formed of sheet metal. Spacers 26 are secured to each blade in Fig.3 the spacers having inwardly directed flanges so as to form hollow chambers. Deflectors 27 are mounted inside each blade and openings 29, 31 are formed in the blade surfaces as shown whereby coolant directed inwardly into the blade cavity 28 is re-directed by the scoop 27 through openings 29 into the chamber formed by the spacer 26. The coolant then re-enters the blade cavity 28 through openings 31 and flows radially outwardly from the cavity. In Fig. 6 a blade shroud ring 42 is secured to the tips of the blades 44 the shroud ring being formed with reinforcing ribs 43. Each blade cavity opens through the shroud ring and a scoop is formed on the concave surface of the blade outwardly of the shroud ring, water being supplied by injectors 52 which discharge into an annular chamber 48 defined between the shroud ring 42 and the stator casing 46, 47. In Fig. 8 each blade 76 is formed with a scoop 92 to collect water discharged from the nozzle 56 and to direct it into the blade cavity as in previous embodiments, but in this case further means in the form of water injection nozzles 57, 58 to supply coolant to the inner ends of the rotor blades are provided. The nozzles 57, 58 are mounted in stator structures 62, 63 and discharge water into annular gutter regions 71, 72 defined by the blade root portions 89 and the side walls 67, 68 of the blade platforms 69. Water passes from gutters 71, 72 through openings (77), (78), 79, 81 and through spaces (84), 86 defined between ribs (87), 88 formed on the root portions 89 and the walls (91) of the blade, the water then discharging through the blade cavity and mixing with the water collected by the scoops 92. Cooling water is also passed through the inlet guide vanes 98 as indicated by the flow arrows. In Figs. 11, 12 (not shown) the rim (108) of the rotor disc is formed with circumferential ridge portions which with the cover plate (109) define circumferential grooves (111), (112), (113) to which coolant is supplied through bores (a), (b), (c), (d) from the annular gutters (103), (104). The blades (107) are mounted in appropriately shaped recesses formed in the ridge portions. Coolant flows from the grooves (111), (112), (113) through openings (114) into the blade cavities. In Fig. 14 (not shown), the blade platform is formed with downwardly extending flanges which define a chamber to which coolant is supplied and from which it passes through bores into the blade cavity. In Fig. 15 (not shown) the blade spacers are formed with downwardly extending flanges which define chambers to which coolant is supplied, similar to Fig. 3, but the internal guides 27 of Fig. 3 are not provided. Coolant is supplied to the spacer chambers from outside the blade.