JPH0368201B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to steam turbines, and more particularly to rotor blades and rotor disks for low pressure turbines.

In order to increase the opening or gap between the rotor disks to provide sufficient opening for machining of the cavity between the disks, the sealing lobes are removable along with the rotor blades so that the gap between the disks is increased. repositioned on the rotor platform section to allow access to the cavity of the rotor.

According to the present invention, the rotor blade structure for a steam turbine includes:
a plurality of discs as part of the shaft fastened to provide sufficient space between the discs to allow machining between the discs;
comprising a plurality of annular rows of rotor blades, the rotor blades having a Christmas tree-shaped root connected to the disk, an airfoil, and a pedestal between the root and the airfoil;
an overhang extending from the platform of each rotor blade, the blades being arranged in an annular row with the overhangs abutting each other, the overhang having a radially outer surface causing the airfoil to forming a continuous ring having a substantially cylindrical outer surface extending axially beyond and surrounding a substantial portion of the space between said discs, the cylindrical outer surface formed by said overhang forming a labyrinth; They cooperate to form a rotating seal between axially adjacent rotor blades.

It is advantageous to fasten the rotor blades in the annular row to a disk integral with the shaft, such that a sufficiently large space is provided between the disks for mechanical finishing of the disks, and each rotor blade is , a root portion coupled to the disk, an airfoil portion, a pedestal between the root portion and the airfoil portion, and an overhang portion extending from the pedestal portion, and the overhang portion is configured to be connected to the blade when the blades are arranged in the blade row. abutting the bulges of the discs to form a substantially continuous ring extending axially beyond the pedestal and surrounding a substantial portion of the space between the discs.

The invention will now be explained by way of example with reference to the accompanying drawings.

FIG. 2 is a perspective view of a portion of an annular array of rotating or rotatable blades 1. FIG. The Christmas tree-shaped root 3 of the rotor blade 1 fits into a substantially identically shaped, lateral-receiving groove 5 provided substantially axially in a disk 7 formed integrally with the shaft 9. The radially outer portions of the rotor blades 3 form airfoils 11 which are spaced apart to allow steam flow to pass between them. A pedestal 13 is provided between the root 3 and the wing-like portion 11, and an overhang 15 integrally formed with each pedestal 13 extends axially from the pedestal.
The radially outer arcuate surface 17 of each flange 15 cooperates with an adjacent flange 15 to form a generally cylindrical surface. Adjacent to the bulge 15 is a stator vane ring or diaphragm 19 that includes a plurality of labyrinth seals 2 that cooperate with the bulge 15 to form a rotating seal between the stages.
1.

Compared to the prior art shown in FIG. 15, the gap between the disks is substantially expanded when the rotor blades are removed, increasing the accessibility of the cavity for finishing operations, increasing steam leakage around the vanes, and eliminating the need for the actual shaft. It can be seen that significant improvements can be made without reducing the directional expansion margin or increasing the radial expansion tolerance of the rotary seal.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of a prior art turbine rotor; FIG. 2 is a perspective view of a portion of a rotor blade row constructed in accordance with the present invention; and FIG. 3 is a turbine disc constructed in accordance with the present invention. and a cross-sectional view of a part of the rotor blade. In the figure, 1 is the rotor blade, 3 is the root, 7 is the disk, 9
11 is a wing, 13 is a platform, 15 is an overhang, 17 is a radially outer arcuate surface, and 21 is a labyrinth seal.

Claims (1)

[Claims] 1. An annular row of rotor blades fastened to a plurality of disks as part of a shaft in such a way that a cavity of substantially circular cross-section sufficiently wide is obtained between the disks to allow machining between the disks. In a rotor blade structure for a steam turbine, the rotor blade includes a Christmas tree-shaped root connected to the disk, an airfoil, and a platform between the root and the airfoil. A projecting portion is formed integrally with the platform so as to extend from the platform, and the rotor blades are arranged in an annular row with the projecting portions abutting each other, and the rotor blades are arranged in an annular row with the projecting portions abutting each other. forming a continuous ring having a substantially cylindrical outer surface extending axially beyond the wing and surrounding a substantial portion of the cavity opening between the disks; A rotor blade structure for a steam turbine, wherein the cylindrical outer surface formed by the overhang portion cooperates with a labyrinth seal and a diaphragm to form a rotating seal between axially adjacent rotor blades.